Author Topic: 540 Coast Regiment  (Read 8474 times)

0 Members and 1 Guest are viewing this topic.

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
540 Coast Regiment
« on: February 05, 2012, 13:21:04 pm »
An ongoing project which I'll add to 'as and when' - transcription of the 'Short Story Of The Guns At Dover Engaged With The Enemy', a brief history of 540 Coast Defence Regiment..



THE HISTORY OF COAST ARTILLERY AT DOVER.   SECTION "A"... OPERATIONAL

At the time of the evacuation of Dunkirk, there were no Coast Artillery Guns on the Kent Coast which had sufficient range to reach the Coast of France, and it was soon apparent that the Germans intended to use the Channel for their shipping. Before long a great deal of important enemy shipping could be seen passing through the Channel. In addition, the enemy commenced to attack our own convoys with "E" Boats, as they passed round the South East Corner of England.

Air reconnaissance and intelligence brought us the information that he was also installing many long range guns in the Pas de Calais Area with which he apparently intended to close the Channel to our shipping.

At this time, to supplement the pre-war installations of 6-inch (15 degree mounting) Batteries and 9.2-inch MkV Batteries we had a number of emergency Batteries of obsolescent 6-inch Naval Mountings. Two modern 6-inch Batteries on 45 degree mountings were being installed rapidly, one each side of Dover Harbour, but their maximun range was only 25,000 yds. The only Battery which could trouble enemy shipping was a 9.2-inch Four Gun Battery on Mk VII Mountings whose installation at st. Margarets Bay was being hastened. This would have a maximum range of 31,600 yds. (A figure which was later increased by the use of super-charge and 8 CRH Shells, to 36,300 yds with new guns).

In September, 1940, War Office approval was given for the installation of two Gun 15-inch Battery between the 9.2 inch Mk VII and 6-inch Mk V Batteries at st. Margarets, and for two Three Gun 8-inch Batteries between Folkestone and Dover. The former had a range of 37,000 yds (increased to 43,000 yds with a super-charge in 1943), and was therefore the only Coast Artillery Equipment which had the range to cross the Channel; the latter had a maximum range of 32,000 yds and due to their siting this was insufficient to reach the channels used by enemy shipping. Although these 8-inch Batteries fired in an A.A. role (they had 70 degree of elevation) and had one short engagement with an "E" Boat, they took no other part in the Actions against Enemy shipping and shore installations - and are not mentioned again.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #1 on: February 05, 2012, 19:00:13 pm »
To complete the picture of the heavy Guns round Dover - two 14-inch Guns on experimental mountings were installed near St. Margarets. These only had a counter-battery role, in conjunction with three Railway Mountings, and having no fire control equipment did not engage any moving sea target. They were manned by Royal Marines personnel.

The history of the engagements against enemy vessels in the straits and against shore batteries in the Pas de Calais Area can well be divided into three separate parts, namely

Part I - Actions in 1942
During this period our own installations were being completed, (the 15-inch Battery was not ready to fire until August), Radar Sets were being tried out, and drills were being evolved.

In all, 20 actions took place :-
6-inch Battery •••••••••••• 4.
9.2-inch Battery •••••••••• 6.
15-inch Battery ••••••••••• 2.
9.2-inch and 15-inch •••••• 8.

Part II - Actions in 1943
During this year drills were improved as Radar Sets developed. Enemy vessels started taking avoiding action.

In all, 18 actions took place :-
6-inch Battery •••••••••••• 2.
9.2-inch Battery •••••••••• 2.
9.2-inch and 15-inch •••••• 14.

Part III - Actions to 17 September, 1944.
During this period of nine months, Coast Artillery had a much greater number of 'confirmed' successes, both against shipping and shore installations, although the volume of enemy shipping passing through the Straits was greatly decreased.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #2 on: February 06, 2012, 17:58:15 pm »
Part 1.

At the beginning of 1942, the 6-inch Battery was fully installed and work on the 9.2-inch Battery was almost complete. However, communications from the F.C. Post to Batteries were only just being connected up and in the first two actions it was not possible to use the F.C. Post, all orders being passed direct from the Army Plotting Room in Dover, to the Battery concerned.

The year opened with a minor engagement by the 6-inch Battery against "E" Boats on the 6th February. Just under a week later, on 12th February the 9.2-inch Battery fired for the first time against the "SCHARNHORST" and "GNEISENAU". It was later credited with having scored 4 hits in this action, but little damage would be done by a 9.2-inch shell at extreme range against this type of target.

As the result of the escape of these two prize vessels of the German Navy, all eyes focused on the Coast Artillery installations in the Dover Area, and every effort was made to speed up the completion of the 15-inch Battery. During the next four months both 15-inch Mountings were proofed, and fire control equipment was hastened and installed. Meanwhile, minor engagements by the 9.2-inch and 6-inch Batteries continued.

On the night of the 2/3rd July 1942 the 9.2-inch Battery fired its first prolonged action against a convoy of 12 small vessels. Five days later it fired again at a medium sized vessel, but in neither case was the opposition considered to be of sufficient importance to warant the use of the 15-inch Battery which was now ready for action.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #3 on: February 07, 2012, 16:35:58 pm »
On 13th August, 1942 both the 15-inch and the 9.2-inch Batteries were ordered to engage two medium sized vessels and for the first time the fire command was tried out as a complete unit. Reports of fall of shot indicated that 16 straddles and one hit had been obtained. In addition it had been learned that the control of two Batteries from the F.C. Post was not only feasible, but fairly straight forward, provided three Officers were employed there.

Shipping movements in the enemy shipping lanes were fairly heavy at this time, and three further engagements took place prior to 24 August, two of which were against German "E" and "R" Boats on minelaying expeditions in the vicinity of Dover Harbour. These latter two are mentioned as they brought the first 'proved' success to the Fire Command, when on the night of 16th August, 1942 an "R" Boat was sunk by the 6-inch Battery, survivors being collected by the Royal Navy.

Four further actions took place prior to the close of 1942. Results were inconclusive, but they served to enable the Fire Command to improve its drill, and to study the tactics that were being employed by the enemy. At the close of the year it had become obvious that

i. The enemy decided to pass a lot of shipping through the Straits, to relieve his sorely tried inland transport system.

ii. That he was of the opinion that it Was only safe to allow ships to move between Boulogne and Calais during the period of least light (i.e. approximately 5 days either side of the new moon).

iii. That the Coast Artillery were definitely worrying him, for he was retaliating with heavy counter battery fire from his own shore installations, and the vessels themselves were devising new methods of taking "avoiding action".
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #4 on: February 08, 2012, 09:33:29 am »
Part II.  The Year 1943.

Actions during 1943 were fairly evenly spaced out during the year, and consisted of one or two in each "dark period". Results from these actions were very difficult to obtain, and little concrete proof will be found until German records have been thoroughly sorted and analysed. However some confirmation has been obtained of the following :-

9 Feb 43. A small 500-ton coaster was engaged by the 6-inch Battery and Was seen wrecked off Calais the following morning.

14 Feb 43 2 medium sized vessels were engaged by the 9.2-inch and 15-inch Batteries and a fire was seen from the cliffs during the action just after straddles had been reported.

2 Mar 43 )
5 Apr 43 ) On each occasion medium vessels (approx 350-ft long) were engaged, and during the passage reduced speed until they were almost stationary. After the action on 5 Apr R.A.F. reconnaissance planes were unable to locate the vessel in any harbour in the vicinity, the following day.

1 May 43. An escort vessel of a convoy was almost certainly destroyed, and the larger vessel probably damaged.

4/5 Jul 43 During a combined action with our own MTBs against two enemy destroyers, the leading MTB reported that one destroyer was hit by our gunfire.

4 Sep 43. During an engagement of two medium sized vessels, one appeared to drift away from the shipping lane, and sink.

4 Oct. 43 After an action against an enemy merchantman known as "M.10" this vessel crawled towards Calais Harbour, at 1 knot, and was finally towed in.

25 Oct 43 A message was intercepted saying that one of the escort vessels in a convoy had been sunk by gunfire.


Throughout the period it was continually necessary to alter the tactics employed, in order to try and counter the latest attempt at "avoiding action" that the enemy had devised. The year closed with a large merchantman in Boulogne Harbour. This vessel, the "S.S. MUNSTERLAND" had already made two abortive attempts to run the gauntlet to Calais, but had on each occasion turned back, just before rounding Cap Griz Nez.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #5 on: February 09, 2012, 09:17:13 am »
Part III.   The 9 months to 17 Sep 44.

1944 opened with high hopes. The "MUNSTERLAND" was expected to give the coast guns an ideal opportunity of proving their accuracy. The dark period did not commence until about the 22 Jan., and so when the report was received in the early hours of 20 Jan that she had left Boulogne, the feeling was that she would probably turn back for the third time. However, she rounded Griz Nez soon after 0300 hrs and was quickly engaged by the 15-inch Battery. The 9.2-inch Battery was just unable to make the range to her but fired three salvoes at escorting vessels. The "MUNSTERLAND" was hit shortly after rounding the headland, and was sunk off Cap Blanc Nez, the wreck being photographed at first light by the R.A.F. It is almost certain that a 1,000 ton vessel in the same convoy was also destroyed.

After this vessel, almost all shipping moving up and down the Channel on the German side consisted of fast moving destroyers or Sperrbreckers, very difficult targets to damage at 20 miles range due to their speed and manoeuvreability. One success was established in March when a tanker came through the Straits at a more normal speed and was believed to have been sunk off Calais.

From April until the end of August still less shipping was located, and although engagements took place against another tanker, a small merchant vessel and two more destroyers, on all occasions but one the 9.2-inch guns fired by themselves at maximum range. They were using a semi-streamlined shell, and a super-charge, and their accuracy, especially with worn guns is greatly diminished under these conditions. It is probable that the merchantman was damaged, but otherwise no serious damage can be claimed against these vessels.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #6 on: February 12, 2012, 09:35:45 am »
The month of August saw the Allies advancing rapidly towards the Pas de Calais. Ports in Northern France west of Boulogne had been falling into Allied hands with a delightful regularity, and little "through" traffic could be expected. Shipping of all descriptions, however, was collecting in Boulogne Harbour, and it was expected that the Germans would try to stage a sea evacuation from this port. This they did, on the night of 1/2 Sep 44, with devastating results. Eleven vessels were definitely sunk by gunfire and were admitted lost by the German authorities, but, in all probability a far greater number of vessels were disposed of. As one Radar operator stated at the time, "there were so many vessels packed together, it was hardly sporting to fire"! During this action, the German batteries staged a very strenuous "hate"  against the Fire Command and did some superficial damage in the 9.2-inch Battery. As a result the 15-inch Battery were ordered to retaliate, in conjunction with the Royal Marine Guns which were firing for the first time since 1941. 10 salvoes were dropped in each of three enemy sites. It is probable that one of the 16-inch enemy guns was damaged, as it did not fire again for four days, while the other guns in this battery fired daily on the least provocation.

Throughout August the Germans had been firing intermittently into the towns of Dover, Folkestone and Deal, and in good visibility had landed a few salvoes near our convoys which now steamed up and down the channel, regardless of anything. But after the attempted evacuation of Boulogne, the Germans fired all day, and every day at anything they could see. On the afternoon of 3 Sep 44, having engaged a convoy shortly after mid-day, they started random firing on land, and V.A. Dover asked for retaliatory fire from the 15-inch Battery, and the 14-inch Guns of the Royal Marines. An hour's duel ensued, and on this occasion the Germans concentrated on the 15-inch Battery. Although damage to the equipments was nil, it must be stated that his shooting was superb, and one magazine, and three huts were hit. It was a great consolation on this afternoon that his shell, as on the night of' the 1/2 Sep did so little damage on bursting, or otherwise two of the 9.2-inch guns, and two magazines might by now have been out of action.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #7 on: February 13, 2012, 17:46:21 pm »
During the night of the 4/5 Sep enemy "R" and "E" boats were causing a little trouble, and were consequently engaged by the 9.2-inch Battery. Again the German long-range guns opened up seriously, and the 15-inch retaliated, but after 45 minutes the Germans quietened down. As we were out-gunned by about 8 or 10 to 1, we were only too anxious to stop, thereby reducing the chances of damage done in the neighbouring towns.

From 5 Sep to 17 Sep the Germans fired almost daily, but by now the 15-inch Guns were in their last quarter of life, and it was necessary to conserve them, for support for the Canadians in their final assault on the Pas de Calais. This was scheduled for the morning of the 17th., when firing was due to commence at 1000 hrs , and continue to a timed programme until 1230 hrs. The weather was fine, and visibility was in the neighbourhood of 40,000 yds, so it looked as if our final shoot would be "Target visible", although the "Target" was not one that had been envisaged in the Coast Artillery manuals. To assist in correcting the fire, an aircraft was to spot, and was in direct R/T communication with the Army Plotting Room.

No 2 Gun of the 15-inch Battery scored a success against No. 2 of the German 16-inch Battery, its shell exploding right inside the German emplacement, and sympathetic detonation of German ammunition wrecked the mounting. At 1230 hrs the firing finished, and it looked as if the last round had been fired from the Dover Guns. The 15-inch were fast approaching their condemning limit, and supercharge ammunition was running short. However at 1400 hrs that afternoon further support was required, and as a result 6 more salvoes were fired, before the guns finally refused to "make" the required range, and the "cease fire" was sounded.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #8 on: February 14, 2012, 08:36:28 am »
And so the Battle of the Straits was over. After some 56 actions, in which 1243/15-inch, 2248/9.2-inch and 73/6-inch shells had been fired, the gunners relaxed. To this day their full successes are not known, but 28 vessels sunk and a 16-inch gun completely wrecked definitely stand to their credit.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #9 on: February 15, 2012, 08:52:59 am »
THE HISTORY OF COAST ARTILLERY AT DOVER.                    SECTION 'B'...TACTICAL

In order to study the tactical handling of Coast Artillery at Dover in its Counter-bombardment or "Long Range" role, it is convenient to divide the problem up into the following main headings :-

i      Use of Rangefinding data.
ii     Communications required.
iii    Methods of obtaining fall of shot observations.
iv    Enemy methods of taking "avoiding action".

However, before studying these in detail, it would be wise to consider for a few moments how the layout in the Eastern Counter Bombardment Fire Command differed, even in its early stages, from any previously conceived idea of the ideal Layout for a counter-bombardment fire command.

Although, at the beginning of 1942, the Fire Command was fully equipped, or had authorisation for the installation of all equipment normally associated with a counter-bombardment fire command on 1939 scales, the importance of Radar had already been realised. Only one Radar set had to date been installed (N.T. 284), but the Fire Command had the use of a second equipment (M-type) situated at FAN BAY, and run by A.O.R.G. for research purposes. Each battery had a visual B.O.P. with the latest type of P.F., and there was a full Fortress system nearing completion, but it was realised that the chances of the target being "visible" were small, and that Radar would almost certainly be the normal method of rangefinding.

This introduction of Radar made one further big difference, as it allowed for the possibility of firing by night. At such times it would be pointless to man the visual. B.O.P's and furthermore war establishments would require adjustment, as all C.B. Fire Commands were built up on a principle of two watches, instead of the normal three allowed when night firing had to be taken into account. And so the problem opened with the necessity of making a decision as to where was the best place to position the Battery Commander. Prior to the introduction of Radar, he had been in the B.O.P., but now it would seem better that he should go to the B.P.R., and handle the tactical control of his battery from there.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #10 on: February 16, 2012, 10:04:59 am »
How far these thoughts were justified can be seen from the fact that in 50 engagements against shipping, 49 were at night, and the 50th, that against the "SCHARNHORST" and "GNEISENAU", the visibility was less than 5,000 yards, and the equivalent of night conditions were prevailing. As a result, visual rangefinders were never employed, Radar became the only method of rangefinding that needed any serious thought, and the official position for the Battery Commander became the B.P.R., a decision that was taken at a conference at Dover in June 1943.

i. Rangefinding Data.

In the early months of 1942, as has already been stated, only one Radar Set was installed in the Fire Command,and this was connected to the 9.2-inch Battery for operational use. Bearings and ranges were passed by telephone to the B.P.R. where they were applied to a hand-operated displacement corrector, and passed thence by magslip transmission to the Fire Direction Table. The second Radar Set in the area, that controlled by A.O.R.G., was similarly linked. with the B.P.R. of the 6-inch Battery, and could be used when required as the rangefinding set for this battery. For the first two actions, communications between F. C. Post and Batteries were not complete, and as direct lines had been installed between the Army Plotting Room in Dover and the 9.2-inch Command Post, and the 6-inch B.O.P., orders for these actions were passed direct from A.P.R. to the Battery concerned.

Army Plotting Room had at its disposal a number of other Radar Sets, including two "K" type (K.147 and K.148) and a number of "M" type sets which comprised a coast watching chain.

Two procedures for the use of the Radar information had been worked out, which were known as "Procedure "A" and Procedure "B".
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #11 on: February 17, 2012, 17:56:11 pm »
PROCEDURE "A". Was the more authordox (sic) method. A continuous stream of Radar plots taken at 40 sec intervals were passed by telephone to the B.P.R., and applied to the displacement corrector. In addition the some information could be applied on the Fortress Plotter if data was required for another battery, and co-ordinates were passed from the F.P.R. to the Co-ordinate Converter of the battery concerned. This system had the disadvantage of a serious time lag. Both systems had the obvious disadvantage that the information received was not continuous, and therefore operators were compelled to "smooth" thus developing their own rates of change of bearing and range. In addition it was found necessary to run the Fire Direction Table in the "PLOT" position, with the resultant possibility of accumulating large errors.

PROCEDURE "B". Was a procedure by which predictions as to the location of the target at a certain time, were passed to batteries, who were ordered to fire one or more salvoes to arrive at the predicted spot at the 'zero hour' indicated. It had the advantage that the predicted position could be passed to any Battery" whether in possession of Counter-bombardment fire control instruments or not.

Its disadvantages were twofold. Firstly the predictions had to be for some considerable time ahead (usually at least 5 mins), and as the targets were usually fast moving E-boats large errors could creep in. Secondly, the whole procedure depended on perfect communications, and exact timing throughout the whole system.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #12 on: February 18, 2012, 18:26:47 pm »
Procedure "B" Was normally only used when it was difficult to follow a target continuously on the Radar Set, or where the ultimate destination of the target" could be fairly accurately determined, (as in the case of E-boats which passed through the gap in a minefield, or made for a particular buoy.) Although the first success against an E-boat Was obtained with this procedure it was dropped as soon as the performance of Radar improved to the extent that no real trouble was experienced in following any target.

Minor modifications were continually being made in Procedure "A" but the main principle stayed, and soon the label was dropped and this modified Procedure "A" became the standard method of using Radar information. The passing of the information to the Fortress Plotting Room was found to be more satisfactory than direct to the B.P.R., as a more reliable track could be produced, due to the larger scale of the instruments involved. This however put a much greater strain on the F.C. Post communications, and it was found essential to have direct telephonic communication between F.C. Post and all Radar Sets in the Fire Command, the F.C. himself being responsible that each set was laid on the correct target.

By 13 August 42 (when the 15-inch Battery fired for the first time) the F.C' s tactical Radar Set (C.A. No. 2 Mk 1) had been installed in the F.C. Post, enabling the F.C. to study the tactical picture and give valuable aid to the other Radar Sets. An experimental "B" type Radar Set (C.A. No. 1 Mk. II) had been installed in the former M.2 site and the consequent improvement in R/F data supplied from this set was most noticeable, to such an extent that the following modifications to the procedure were immediately decided upon:-

(a) 20 second plots to the F.P.R. or B.P.R. were now a possibility and were used.

(b) The correction that had to be applied. to take up for the lag in the system was reduced from "one minute of travel" to approximately half this amount.

(c) The consequent additional smoothness of the Rangefinding information supplied to the Fire Direction Table now allowed for "Following" on the table instead of "Plotting", thus eliminating a very large possible source of error.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #13 on: February 20, 2012, 12:11:49 pm »
The arrival and installation of "B" type Radar Set as Battery Rangefinders, and the substitution of the hand operated Displacement Correctors by Displacement Correction Calculator, which passed the calculated answer to the B.P.R. by magslip transmission, further improved the Rangefinding data, and lag time was again materially reduced, although it was not completely eliminated until automatic Displacement Correctors (Mark I Special) were installed in the 15-inch and 9.2-inch Batteries in December, 1943.

Meanwhile a further improvement had been made in the Fortress Plotting Room by the introduction of the Fortress Plotter No. 2. Although the full advantage of this was not felt until the magslip co-ordinate transmitters were connected to the receivers on the Co-ordinate Converters in the B.P.R's, yet some considerable improvement was obtained from the passing of bearing and range from the Radar Set by magslip instead of by telephone to the F.P.R. For the first time this Plotting Room was receiving a continuous stream of bearing and ranges, instead of the 40-sec or 20-sec plots. In passing, it should be emphasised that the Fortress System was now working as if it were receiving bearing and range from one low-sited F.O.P., and each Radar Set installed was automatically made an "F.O.P." and shoes were fitted on the Fortress Plotter No. 1, gauges being cut for the No. 2 Plotter. As a secondary method of Rangefinding, this proved to be exceptionally good, and it allowed two Batteries firing at the same target to fire from information from the Radar Set (one Battery via D.C.C. to B.P.R., and the second via Fortress Plotter to C.C.). Although this point may not seem to have a very great advantage, it is on accasions (sic) essential, and it also had the advantage of freeing another Set for fall of shot observations, as it will be seen later that the "B" set was incapable of acting as a Rangefinder and a fall of shot set at the same time.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell

Offline John

  • Editor
  • Prolific Contributor
  • *****
  • Posts: 25161
Re: 540 Coast Regiment
« Reply #14 on: February 21, 2012, 19:05:48 pm »
As more and more Radar sets became available, their control became a big problem. Now that the B.C. was in the B.P.R. and therefore only in touch with his Radar Set by telephone, it had already been found necessary to relieve him of some of the responsibility of controlling the Set, which could best be done from the F.C. Post. Adding this burden on to the responsibilities of the Fire Commander was not however, an ideal answer. And so the following drill was established.

(a) The F.C's tactical set was normally the set that was "on target" first. Once the Fire Commander was satisfied with this, it was made the responsibility of that set to guide the other sets on to the target, or any other target indicated later.

(b) At first the direct lines from F.C. Post to Radar Sets were used for this purpose. Later, however it was found advantageous to 'link' all No's 1 i/c Sets together on a multiple circuit with head and breast telephones. By this means the guiding of each set on to a particular target in a group was found to be accomplished more easily.

(c) As a final check, each set that was acting as a range finder during action passed plots direct to the Army Plotting Room every five minutes. This last check was found to be of assistance, as all sets could then be plotted on the one Plotter in the A.P.R.

Probably the biggest step forward in the perfection of Rangefinding data supplied to the B.P.Rs came when the first experimental C.A. No. 1 Mk IV was sent to the Fire Command. This set was far in advance of the 'B' type Rangefinder, and had the added advantage that

(a) It could act as a rangefinder and a fall of shot set at the same time.

(b) A remote display tube could be run from it to any other place required. At the time, the displacement of the display tube from the set was a limiting factor, the greatest displacement allowed being 400 yards. It was therefore impossible to give the B.C. this display, as in the Fire Command all B.P.Rs were far in excess of this distance from the site which had to be chosen for the Set. However the installation of Remote tubes in the F.C. Post greatly assisted the Fire Commander and became a valuable addition to the layout.
"You know, if you don’t read history, you’re a bloody idiot." - James Clavell