40th Anti-Aircraft Brigade

The 40th Anti-Aircraft Brigade was an air defence formation of Anti-Aircraft Command in the British Territorial Army (TA) formed shortly before the outbreak of the Second World War. Its initial role was to defend Royal Air Force (RAF) airfields in East Anglia. Later it commanded part of the searchlight belt protecting The Midlands. In 1944 the brigade was moved south to protect the embarkation ports for Operation Overlord and to defend against V-1 flying bombs in Operation Diver. It was briefly reformed in the postwar TA.

Origin The brigade was formed on 28 September 1938 at Boston Lodge, South Ealing in West London, under the command of Brigadier O.W. Nicholson (Territorial Army). It was part of 2nd AA Division, with the following searchlight units under command:Frederick, pp. 1050–1.AA Command 3 September 1939 at Patriot FilesRoutledge, Table LVIII, p. 376.Routledge, Table LX, p. 378. 33rd (St Pancras) Anti-Aircraft Battalion, Royal Engineers (RE) – formed in 1935 from the 19th London Regiment (St Pancras)Litchfield, p. 171.19th London at Regiments.org 332, 333 & 334 AA Companies, RE 36th (Middlesex) AA Bn, RE – formed in 1936Litchfield, p. 178. 317, 345, 346, 424 AA Companies, RE 58th (Middlesex) AA Bn, RE – formed in 1938 as a duplicate of 36th Bn 344, 425, 426 AA Companies, RE 9th Bn Middlesex Regiment (60th Searchlight Regiment) – infantry battalion converted in 1938Litchfield, p. 179.9th Middlesex at Regiment.org 429, 439, 431 Companies 10th (3rd City of London) Bn Royal Fusiliers (69th Searchlight Regiment) – infantry battalion converted in 1938Litchfield, p. 174.3rd City of London at regiment.org 456, 457, 458 Companies 40 AA Brigade Company Royal Army Service Corps

Although the brigade's units were all from London and Middlesex, its war station was at RAF Duxford, with the searchlight detachments defending RAF stations across East Anglia.

Mobilisation

While the brigade was forming the TA's AA units had been mobilised on 23 September 1938 during the Munich Crisis, with units manning their emergency positions within 24 hours, even though many did not yet have their full complement of men or equipment. The emergency lasted three weeks, and they were stood down on 13 October.Routledge, pp. 62–3. In February 1939 the existing AA defences came under the control of a new Anti-Aircraft Command. In June, as the international situation worsened, a partial mobilisation of the TA was begun in a process known as 'couverture', whereby each AA unit did a month's tour of duty in rotation to man selected AA gun and searchlight positions. On 24 August, ahead of the declaration of war, AA Command was fully mobilised at its war stations.Routledge, pp. 65–6, 371.

Battle of Britain and Blitz 40 AA Brigade largely operated as a 'light' AA brigade composed of searchlight (S/L) and light AA gun (LAA) units. By the summer of 1940, all searchlight regiments had been transferred to the Royal Artillery (RA). As more LAA units became available, they were distributed to defend Vulnerable Points (VPs) such as factories and airfields. The S/L layouts had been based on a spacing of , but due to equipment shortages this had been extended to .Routledge, pp. 388-9. After the intense period of activity against airfields during the Battle of Britain, the German Luftwaffe switched to night raids against London and other cities (The Blitz). In November 1940 the S/L layout was changed to clusters of three lights to improve illumination, but this meant that the clusters had to be spaced apart. The cluster system was an attempt to improve the chances of picking up enemy bombers and keeping them illuminated for engagement by AA guns or RAF Night fighters. Eventually, one light in each cluster was to be equipped with searchlight control (SLC) radar and act as 'master light', but the radar equipment was still in short supply.Pile's despatch.Collier, Chapter XVI.Collier, Chapter XVII.Routledge, p. 393.

Order of Battle 1940–41 By the time the Blitz ended in May 1941, 40 AA Bde's composition was as follows:2 AA Div at RA 39–45.Routledge, Table LXV, p. 396.Farndale, Annex D, p. 258.Order of Battle of Non-Field Force Units in the United Kingdom, Part 27: AA Command, 12 May 1941, with amendments, The National Archives (TNA), Kew, file WO 212/79. 78th (1st East Anglian) Heavy Anti-Aircraft Regiment, Royal Artillery – formed in 1938 by conversion of 84th (1st East Anglian) Field Regiment, RALitchfield.Norfolk Artillery Volunteers at Regiments.org78 HAA at RA 39–45. 243 HAA Bty 244, 409 HAA Btys – attached to 32 (Midland) AA Bde 245 HAA Bty – attached to 41 (London) AA Bde 30th Light AA Regiment, RA – newly raised in August 1939, joined 40 AA Bde October 1939; one Troop deployed to each of 10 RAF stationsLitchfield, p. 69. 117, 118, 120 LAA Btys 36th (Middlesex) Searchlight Regiment, RA – see above36 S/L at RA 39–45. 317, 345, 346, 424 S/L Btys 64th (The Essex Regiment) Searchlight Regiment, RA – formed in 1938 from 1/6th Bn Essex Regiment; transferred from 41 AA Bde in November 1940Litchfield, p. 71. 441, 442, 443 S/L Btys 72nd (Middlesex) Searchlight Regiment, RA – raised in 1938; transferred from London in November 1940 465, 466, 467, 510 S/L Btys

Mid-War

In the summer of 1941, AA Command began to receive purpose-built SLC radar in sufficient numbers to allow some S/Ls to be 'declustered' into single-light sites. These were redeployed into 'Indicator Belts' of radar-controlled S/L clusters covering approaches to the RAF's night-fighter sectors, repeated by similar belts covering AA Command's Gun Defence Areas (GDAs). Inside each belt was a 20-mile deep 'Killer Belt' of single S/Ls spaced at intervals in a 'Killer Belt' cooperating with night-fighters patrolling defined 'boxes'. The pattern was designed to ensure that raids penetrating deeply towards the Midlands GDAs would cross more than one belt, and the GDAs had more S/Ls at close spacing. The number of LAA units to protect Vital Points such as airfields was growing, albeit slowly.Routledge, p. 99.Routledge, pp. 398–404.

At this stage of the war, experienced units were being posted away to train for service overseas. This led to a continual turnover of units, which accelerated in 1942 with the preparations for the invasion of North Africa (Operation Torch) and the need to transfer LAA units to counter the Luftwaffes hit-and-run attacks against South Coast towns that began in March 1942. By May 1942 the brigade only had two units under command (36th and 64th S/L Rgts), but newly formed units continued to join AA Command, the HAA and support units increasingly becoming 'Mixed' units, indicating that women of the Auxiliary Territorial Service (ATS) were fully integrated into them.Collier, Chapter XX.

Order of Battle 1941–43 During this period the brigade's composition was as follows (temporary attachments omitted):Order of Battle of Non-Field Force Units in the United Kingdom, Part 27: AA Command, 2 December 1941, with amendments, TNA file WO 212/80.Order of Battle of Non-Field Force Units in the United Kingdom, Part 27: AA Command, 14 May 1942, with amendments, TNA file WO 212/81.Order of Battle of Non-Field Force Units in the United Kingdom, Part 27: AA Command, 1 October 1942, with amendments, TNA file WO 212/82.Order of Battle of Non-Field Force Units in the United Kingdom, Part 27: AA Command, 13 March 1943, with amendments, TNA file WO 212/83.Order of Battle of AA Command, 1 August 1943, with amendments, TNA file WO 212/84.

78th (1st East Anglian) HAA Rgt – transferred to 41 AA Bde Summer 1941 243, 244, 245, 409 HAA Btys 30th LAA Rgt – left December 1941, later joined 44th (Home Counties) Division and went to EgyptJoslen, p. 71. 117, 118, 120 LAA Btys 33rd LAA Rgt – from 33 (Western) AA Bde Autumn 1941, left December 1941, later went to IndiaJoslen, p. 523. 67, 68, 132 LAA Btys 96th LAA Rgt – new regiment formed November 1941; left Spring 1942, later went to East Africa CommandFarndale, Annex M.Joslen, p. 491. 80, 299, 300 LAA Btys 454, 479 LAA Btys – joined February 1942 138th LAA Rgt – new regiment formed May 1942'; to 65 AA Bde Summer 1943 454, 469, 470 LAA Btys 458 LAA Bty – joined July 1942 36th (Middlesex) S/L Rgt – to 50 AA Bde September 1943 317, 345, 346, 424 S/L Btys 64th (Essex) S/L Rgt – to 32 AA Bde, May–June 1942; returned by October 1942; to 31 AA Bde August 1943 441, 442, 443 S/L Btys 72nd (Middlesex) S/L Rgt – to 41 AA Bde late 1941 465, 466, 467, 510 S/L Btys 40 AA Brigade Signal Office Mixed Subsection – part of 1 Company, 2 AA Division Mixed Signal Unit, Royal Corps of Signals (RCS)

Later War In 1942 AA Command abolished its hierarchy of divisions and corps, and established a single tier of AA Groups; corresponding to the Groups of RAF Fighter Command. 40 AA Bde came under 5 AA Group based at Nottingham and affiliated to No. 12 Group RAF.Routledge p. 401 & Map 36.

During the summer of 1943, the last of 40 AA Bde's units were transferred away. In November the brigade HQ was given a complete new roster of AA gun units to command, and in January 1944 it was transferred to 2 AA Group. This formation in Southern and South-Eastern England was responsible for defending the assembly camps, depots and embarkation ports for the forthcoming Allied invasion of Normandy (Operation Overlord). In November 1943 it was also ordered to plan for the expected onslaught of V-1 flying bombs (codenamed 'Divers') against London, to which it responded by planning a thick belt of 8-gun HAA positions across the likely flight path, backed by LAA guns. Meanwhile, 2 AA Group had to deal with a sharp increase in Luftwaffe air raids trying to reach London during the winter of 1943–4 (the so-called 'Little Blitz').Routledge, pp. 408–10.

Order of Battle 1943–44

During this period the brigade was constituted as follows:Order of Battle of AA Command, 27 April 1944, with amendments, TNA file WO 212/85. 126th HAA Rgt 423, 425, 426, 431 HAA Btys 127th HAA Rgt 396, 411, 422, 433 HAA Btys 140th HAA Rgt – joined from 65 AA Bde by January 1944 418, 420, 429, 430 HAA Btys 129th LAA Rgt 425, 426, 427, 455 LAA Btys 134th LAA Rgt 192, 275, 287, 475 LAA Btys 135th LAA Rgt 445, 447, 450, 469 LAA Btys

Operation Diver AA Command relieved the burden on 2 AA Group by bringing down 6 AA Group HQ from Scotland and giving it responsibility for the Overlord ports in the Solent–Portsmouth area. 40 AA Brigade and some of its regiments transferred to 6 AA Group in May 1944.Routledge, p. 409.