By the end of 1941 the number of Searchlight Regiments in the Royal Artillery had risen to 71.  A regiment had a strength of 52 Officers and 1622 OR s and was one of the largest regimental level units in the Army, over twice the size of a field regiment.  A regiment was commanded by a lieutenant colonel and consisted of four batteries, each commanded by a major, with a strength of 11 officers and 365 OR s, although there were a number of three battery regiments.  A battery consisted of four troops each with six searchlights and was usually commanded by a captain.  Both the 90 and 150 cm searchlights had ten-man detachments on static sites.  This gave a regiment a total equipment strength of 96 searchlights.  To give you some idea of the size of a searchlight regiment the photo here (Fig 10) is of 342 (M) SL Bty, 93 SL Regt, about which more later.  Just multiply this by 4 and you can see just how big a searchlight regiment really was.

Not only where the regiments large in manpower they were spread over a large geographical area making command and control very difficult. Here (Fig 11) we see the spread of 82nd SL Regt which covered the Wiltshire area from November 1941 until June 1943.

The roles of searchlights had been evolving since the start of the war but the primary role was still the illumination of aircraft at night for recognition and engagement by Anti Aircraft guns and by RAF night fighters.  The secondary roles were:

Coastal Watch
Homing Beacon for stricken Aircraft
Artificial Moonlight
LAA fire - each searchlight detachment was issued a Lewis light machine gun
Intelligence gathering to assist the Observer Corps

Here (Fig 12) we see the layout of a searchlight site in early 1940 and the position the detachment in action:

The Searchlight should be placed on flat solid piece of ground with clear 360 degree visibility.  The sound locator where possible should be located in the path of approaching enemy aircraft, 50 yards forward of the searchlight, and as far way as possible from external noise including wind.  The Generator should be between 200 to 300 yards from the searchlight and the maximum distance from the sound locator.  If possible intervening hedge rows and trees should be used to shield the noise from the searchlight and give overhead camouflage. 

Numbers 1, 4 and 5 work on the searchlight.

Numbers 2 and 3 are the spotters, deployed approximately 30 to 50 yards each side of the searchlight

Numbers 6, 7 and 8 are the sound locator detachment. Their secondary duty is to man the AA machine gun which should be placed as near as possible to them without hindering the locator’s operation.

Number 9 is at the generator.

The main means of communication was by telephone, with both the sound locator detachment and Number 9 having their own lines. The Number 1 has a link with the Troop command post, although this was often manned by the cook when the light was in action. Later in the war sites were issued a No 17 Set radio for communication with troop headquarters.

In more detail:

The No 1 is the detachment commander, normally a sergeant.  One of his responsibilities is discipline. As we see from this photo taken from the 1960 comedy “Light up the Sky”, based on life on a searchlight site, we see the cook, played by Harry Locke, trying to punch the No 1, played by Victor Maddern, for criticising his cooking, while a young Gunner Benny Hill, tries to break up the fight (Fig 13).

The Nos 2 and 3 are the eyes of the detachment, each equipped with a pair of binoculars and a spotting chair, their main role is to search for targets and to help direct the beam on to the target as soon as they see it (Fig 14).

The No 4 is responsible for the proper care and maintenance of the outside of the searchlight and in action he is responsible for tracking and keeping the beam on to the target with assistance from the sound locator and the spotters (Fig 15).

The No 5 is responsible for the care and maintenance of the lamp, all electrical circuits, and the inside of the projector barrel.  Most importantly, in action he/she is responsible for the arc unit ensuring that it is burning correctly and efficiently and that the carbons don’t burn out.

The sound locator detachment is a three man team. The No 6, a JNCO, is the detachment commander and also the 2IC of the searchlight detachment. The No 7 is responsible for tracking sound in the azimuth and informing the No 6 when on target, and No 8 for tracking sound in the elevation.  The sound locator detachment is also responsible for manning the Anti-Aircraft machine gun on orders from the No 1.

The No 9 is responsible for the maintenance and the technical working of the generator or generator lorry. During the hours of darkness he must make sure the engine is capable of taking full load at a moment's notice, and it must therefore be kept warm and started regularly, remembering the early generators were hand-cranked to start.

(Video Clip 3 - Australian Unit Deploying)

At the beginning of the war the defensive plan for searchlights was to have great belts of the lights across the country with a searchlight every 3,500 yards.  However, there was such a shortage of searchlights that the interval had to be increased to 6,000 yards.  Gun Defended Areas such as cities and ports, for example, were kept at 3,500 yards where possible.  This layout did have it problems and some lessons were learnt in the first real brush with the Luftwaffe during the Battle of Britain.

The Battle of Britain started slowly in June 1940 with the enemy raiding by day, and even after switching to night raids, the Luftwaffe still only attacked ports and shipping.  In July the enemy switched back to daylight raids which were now heavier, averaging 20 aircraft, but still concentrating on ports and extending to include the industrial centre of the Midlands.  Even after this short time, the searchlights detachments were starting to suffer from having to be awake all day augmenting the Observer Corps and manning their machine guns and then being on duty all night manning he lights. During August the raids grew in number and intensity, with the list of targets broadened to include airfields and radar sites, and heavy fighter escort. The number of aircraft used to attack the fighter stations grew and some raids had in excess of 200 aircraft, it was now obvious that the Luftwaffe were intent on trying to destroying the RAF on the ground.  While this battle was being fought mainly during the day by the RAF, searchlight sites were playing their part with intelligence reports and even shooting down a number of enemy aircraft.

On 15 Sep 1940 the Luftwaffe threw everything they had at Britain. The RAF was ready for them and in the fighting that day the RAF reported they had shot down between 60 and 80 aircraft.  With the RAF concentrating on protecting their airfields it was often left to Ack Ack Command to defend the ports and industry.  In the three and half months of the Battle Ack Ack command had destroyed 190 aircraft and although statically low, General Pile later stated in his autobiography:

“There is no doubt that the RAF played the dominant role in the great victory, nor is there any doubt of the heroic fighting qualities of the pilots who took part in that battle. Yet without the ground defences, the Battle of Britain could not have been won by the fighter pilots, any more than the battle of El Alamein could have been won by the infantry and tanks without the Gunners.”

The next big trial for the searchlight detachments was the Blitz, an eight month nocturnal battle over the cities of Britain. Although London had had a taste of what was to come in early July it was not until September 1940 that the Luftwaffe really started the raids in earnest.  Although the searchlight layout was tight in London, over the rest of the Great Britain due to the lack of searchlights it was patchy to such of an extent it became a help to the enemy.  German pilots where able to use the location and density of searchlights as an indication to the location of high priority targets.  Many searchlight units were ordered to black-out, which did not help the moral of the Gunner detachments or the civilian population closest to the blacked-out lights. However this blackout did not seem to help and on 22 Sep they were order to end the blackout and to re-engage the enemy.

The more powerful 150cm Searchlights were now being issued in quantity but the searchlights of Ack Ack Command were still not having the effect hoped for.   In November 1940 the searchlights in the 11 Group area were reorganised and ordered to form clusters in sites with one 150cm and two 90cm searchlights on each site, each site being 10,400 yards apart.  This applied to searchlights both in Gun Defended Areas as well as the belts to try and combat the recognition of defended areas by enemy bombers.  Until then the searchlights sites had been controlled and named by the AA divisions.  As part of the changes they were more closely integrated with the RAF.  Searchlight Sector Control Rooms were now co-located with the RAF where possible.  Also all the searchlight site names were allocated an alpha-numeric code made up of the 2 letter Sector Code, such as DX - Duxford or MW - Middle Wallop, and a 4 or 3 digit number the first 1 or 2 digits for the battery the third for the troop and the forth for the site.

In February 1941, at the height of the Blitz, Ack Ack Command got the increase in size that General Pile had been hoping for, to three corps, a total of 12 divisions. More important was the realignment of the divisional boundaries to better match the RAF Group boundaries (Fig 16).  Also during February it became evident that the clustering trial, while having merit, was not producing the results that were hoped for so a new searchlight layout was designed.

By August 1941 as the Blitz started to diminish, a new searchlight plan was drawn up (Fig 16). The Gun Defended Areas kept their own searchlight units, while the remainder covered Britain south of the River Tees, less for two small areas in the Midlands and Wales. There were two densities, Killer Belts of one searchlight every 6,000 yards approximately and Indicator Belts of one every 10,400 yards, these to be equipped with the new SLC radar guided searchlight when it became available, however due to the lack of manpower the full coverage was never achieved (Fig 17).

FWL-Wartime Record.