1st AA Division was organised on 15 December 1935 at Hillingdon House, RAF Uxbridge (at that time the headquarters of the Royal Observer Corps).
Responsible to London District but under the operational control of RAF Fighter Command, the Division's role was to command the growing number of Territorial Army (TA) anti-aircraft gun and searchlight units around London (2 AA Division was in formed in 1936 to cover the rest of the country). The headquarters of the division was formed by converting 47th (2nd London) Infantry Division, whose General Officer Commanding, Major-General R.H.D. Thomson, continued as GOC of the new formation. Thomson had been Commander TA Air Defence Brigades and Inspector of Regular AA Units, and thus already responsible for the four brigades or 'groups' that comprised the division. He also chaired the War Office committee on expansion and mobilisation of TA AA units, which sat from 1935 to 1937. Tompson was followed in 1937 by Maj-Gen Sir Frederick Pile, who was promoted in 1939 to command the whole of Anti-Aircraft Command.
1 AA Division was initially composed of the following formations and units:General Officer Commanding: Major-General R.H.D. Thomson
26th (London) AA Group organised 16 December 1935 at the Duke of York's Headquarters, Chelsea
51st (London) Anti-Aircraft Brigade, Royal Artillery (TA) – AA guns
52nd (London) Anti-Aircraft Brigade, RA (TA) – AA guns
53rd (City of London) Anti-Aircraft Brigade, RA (TA) – AA guns
54th (City of London) Anti-Aircraft Brigade, RA (TA) – AA guns
26th (London) Anti-Aircraft Battalion (London Electrical Engineers), Royal Engineers (TA) – searchlights
27th (London) Anti-Aircraft Battalion (London Electrical Engineers), RE (TA) – searchlights
27th (Home Counties) AA Group organised 15 December 1935 at RAF Kenley, Surrey
60th (City of London) Anti-Aircraft Brigade, RA (TA) – AA guns
30th (Surrey) Anti-Aircraft Battalion,RE (TA) – searchlights
31st (City of London Rifles) Anti-Aircraft Battalion, RE (TA) – searchlights
34th (The Queen's Own Royal West Kent) Anti-Aircraft Battalion, RE (TA) – searchlights
35th (First Surrey Rifles) Anti-Aircraft Battalion, RE (TA) – searchlights
28th (Thames and Medway) AA Group
55th (Kent) Anti-Aircraft Brigade, RA (TA) – AA guns
58th (Kent) Anti-Aircraft Brigade, RA (TA) – AA guns
61st (Finsbury Rifles) Anti-Aircraft Brigade, RA (TA) – AA guns
29th (Kent) Anti-Aircraft Battalion, RE (TA) – searchlights
32nd (7th City of London) Anti-Aircraft Battalion, RE (TA) – searchlights
29th (East Anglian) AA Group organised January 1936 at RAF North Weald, Essex
59th (The Essex Regiment) Anti-Aircraft Brigade, RA (TA) – AA guns
28th (Essex) Anti-Aircraft Battalion, RE (TA) – searchlights
33rd (St Pancras) Anti-Aircraft Battalion, RE (TA) – searchlights
36th (Middlesex) Anti-Aircraft Battalion, RE (TA) – searchlights
1st Anti-Aircraft Divisional Signals, Royal Corps of Signals (RCS), Regency Street, London SW1
1st Anti-Aircraft Divisional Royal Army Service Corps (RASC), Crescent Road, Plumstead
(In 1938 the Royal Artillery replaced the unit designation 'Brigade' by 'Regiment', which allowed the AA Groups to take the more usual formation title of Brigades.)
The AA Divisions were unlike field formations: they were established to organise training and later exercise operational command in the static conditions of home defence, but relied entirely on the Home Forces commands for logistic support, supplies, and heavy repairs.
The TA's AA units were mobilised on 23 September 1938 during the Munich Crisis. The staff of 1st AA Division now had to implement the Tompson Committee's plan. The call-out of key parties by telephone and telegram went well, and they assembled at their drill halls within a few hours. Because the units possessed only a small scale of transport, elaborate plans had been made to requisition civilian vehicles, ranging from heavy lorries to buses and private cars. Equipment was drawn from mobilisation stores, and the detachments ferried out to their war stations. Despite some failures and problems, the emergency positions covering London were manned and most of the equipment was in place within 24 hours. The emergency mobilisation lasted nearly three weeks before the TA units were released on 14 October. The experience brought about improvements in equipment scales, and a rapid expansion of AA defences brought many new AA gun and searchlight units into existence, some by conversion of TA infantry battalions.
The existing divisions and brigades were expanded, and the whole AA defence of the United Kingdom was taken over by Anti-Aircraft Command on 1 April 1939. A new 6th AA Division was formed by duplicating 1st AA Division's HQ at Uxbridge. 6th AA Division took over responsibility for defending the Thames Estuary and the adjacent areas of Essex and North Kent, allowing 1st AA Division to concentrate on the defence of London. 27th, 28th and 29th AA Brigades were transferred to the new formation.
The deterioration in international relations during 1939 led to a partial mobilisation in June, and a proportion of TA AA units manned their war stations under a rotation system known as 'Couverture'. Full mobilisation of AA Command came in August 1939, ahead of the declaration of war on 3 September 1939.
When the UK declared war on 3 September 1939, 1 AA Division had the following composition:
GOC: Major-General F.L.M. Crossman, DSO, MC
HQ: Hillingdon House, RAF Uxbridge26th (London) Anti-Aircraft Brigade, Brompton Road, London SW3 – heavy AA guns
Brigadier Robert Whittaker (18 January 1939 – 11 November 1940)
53rd (City of London) Anti-Aircraft Regiment, RA (TA)
86th (HAC) Anti-Aircraft Regiment, RA (TA)
88th Anti-Aircraft Regiment, RA (TA)
38th Light Anti-Aircraft Brigade, organised 28 September 1938 at Duke of York's Headquarters, Chelsea, by duplication of 26 AA Bde – searchlights
26th (London Electrical Engineers) Anti-Aircraft Battalion, RE (TA)
27th (London Electrical Engineers) Anti-Aircraft Battalion, RE (TA)
75th (Middlesex) Searchlight Regiment, RA (TA)
48th Anti-Aircraft Brigade, organised 28 August 1939 at Lewisham – heavy AA guns
54th (City of London) Anti-Aircraft Regiment, RA (TA)
60th (City of London) Anti-Aircraft Regiment, RA (TA)
97th (London Scottish) Anti-Aircraft Regiment, RA (TA)
99th Anti-Aircraft Regiment, RA (TA)
49th Anti-Aircraft Brigade, organised 28 August 1939 at Lower Belgrave Street, London SW1 – heavy AA guns
51st (London) Anti-Aircraft Regiment, RA (TA)
52nd (London) Anti-Aircraft Regiment, RA (TA)
84th (Middlesex, London Transport) Anti-Aircraft Regiment, RA (TA)
In August 1940 the RE 'Anti-Aircraft' (searchlight) battalions became regiments of the RA. Royal Artillery AA units were now designated Heavy Anti-Aircraft (HAA), Light Anti-Aircraft (LAA), or Searchlight (S/L) regiments and batteries.
1st AA Division had established a control centre at a disused Underground station at Brompton Road. The tunnels, subways and lift-shafts were adapted to provide bomb-proof accommodation for a Central Operation Room reporting direct to HQ No. 11 Group RAF at Uxbridge, and four Gun Operations Rooms (GORs) subdividing the London Inner Artillery Zone (IAZ). An elaborate network of dedicated telephone lines was laid by the General Post Office and Royal Corps of Signals, linking the AA sites, including many isolated searchlight positions.
On mobilisation in August 1939, 1st AA Division controlled 159 HAA guns, 96 searchlights, and a mixture of LAA guns (1 x 3-inch, 1 x 40mm Bofors and 52 light machine-guns (LMGs)). Most of the HAA guns were assigned to the IAZ, with one troop of 4 guns at RAF Fighter Command HQ at Stanmore and four more (16 guns) at airfields.
The London IAZ extended from Cheshunt and Dagenham in the east to Bexley and Mitcham in the south and to Richmond and Northolt in the west. The HAA positions were sited to produce an optimum density of fire of at least 16 guns engaging any one raid simultaneously. It had been intended that 26th AA Brigade would control the whole zone, but it proved too complex for one HQ, and in September 1939 it was divided among three: 26th AA Bde (34 sites disposed to north and east), 48th AA Bde (28 sites to south-east and south), and 49th AA Bde (12 sites to west). 26th AA Brigade still had the heaviest concentration of guns, mainly static 3.7-inch and 4.5-inch guns, with sites being increased from four to eight guns each. 48th AA Brigade had a mixture of 3.7 and 4.5-inch guns, half of the former being mobile. 49th AA Brigade had older 3-inch guns, but also controlled a higher proportion of LAA sites at Vital Points (VPs). Superimposed on the IAZ were the 73 searchlight sites controlled by 38th AA Bde.
On 5 June 1940, after the British Army had been evacuated from Dunkirk and the Battle of Britain was about to start, 1st AA Division comprised 45 4.5-inch, 39 3.7-inch and 26 3-inch HAA guns, with three 3-inch, 19 Bofors, three twin Vickers and 185 LMGs in the LAA role, together with 240 90 cm searchlights. On 11 July, the division's guns were disposed with 92 defending London, 28 at Slough, 4 at Hounslow, 4 at Stanmore, and 34 others dispersed to VPs.
While the Luftwaffe attacked RAF airfields, only the guns of 48th AA Bde in south-east London were engaged. On 1 September, over 200 aircraft attacked Maidstone, RAF Biggin Hill, RAF Kenley and Chatham: the guns of 1st and 6th AA Divisions broke up the attacks but Kenley and Biggin Hill were badly hit. The following day a raid up the Thames estuary reached the edge of the London IAZ and were engaged by 26th AA Bde. Between 11 and 15 September, massed raids approached London, but running battles with RAF fighters broke up most of the raids before they reached the IAZ, where they were engaged by 48th AA Bde.
By 30 September, when the Battle of Britain was effectively over and the Luftwaffe had switched to night raids over London (The Blitz), 1st AA Division had 233 HAA guns, 60 LAA guns, 161 LMGs and 242 searchlights covering the London IAZ, together with 36 HAA guns defending Slough, Langley, Weybridge and airfields.
In the absence of inland radar coverage, 1st AA Division's Chief Signals Officer, Lt-Col G.C. Wickens, devised a system of 14 fixed base-lines of sound locators to detect night raids approaching the IAZ. These were linked by automatic telephone equipment to the Brompton operations room, where the angular plots were resolved to indicate grid squares where the HAA guns in range could fire an unseen barrage. This 'Fixed Azimuth' system came into action in June 1940, in time for the opening of the night Blitz on London. It was later replaced as searchlight control (SLC) and gunlaying (GL) radar systems were introduced.
However, the performance of the AA defences in the early weeks of the Blitz was poor. AA Command moved 108 HAA guns to the IAZ from other divisions, and arranged 'fighter nights' when the guns remained silent and RAF night fighters were allowed to operate over London with the searchlights. GL radar, modern sound-locators and larger (150 cm) searchlights were introduced as rapidly as possible. From September 1940, rocket projectors (Z Batteries) were introduced, equipped with rocket projectiles, and by February 1941, SLC began to be issued. The number of raiders shot down steadily increased until mid-May 1941, when the Luftwaffe scaled down its attacks. During 1941 increasing numbers of women of the Auxiliary Territorial Service (ATS) took over roles in AA Command. Where they were integrated into units these were designated 'Mixed' ('M').
Towards the end of 1940, at the height of The Blitz, AA Command formed three AA Corps: 1st AA Division formed part of 1 AA Corps in Southern England.
From this time 1st AA Division's composition was as follows:GOC: Major-General Robert Whittaker (12 November 1940 – 31 December 1941)
26 AA Brigade – part of London IAZ
Brigadier S.K. Thorburn (12 November 1940 – 19 February 1943)4th HAA Regiment, RA – a Regular unit returned from Dunkirk; left in June 1941 for West Africa Command and the Malta garrison
52nd (London) HAA Regiment, RA (TA) – left Summer 1941 for 9th AA Division
86th (HAC) HAA Regiment, RA (TA) – rejoined by February 1941; to 49 AA Bde late 1941
119th HAA Regiment, RA (TA) – formed December 1940; left by May 1941 for 8th AA Division
62nd LAA Regiment, RA (TA) – formed October 1940; left in June 1942 for 9th AA Division
6th AA Z Regiment, RA – formed September 1940
88th HAA Regiment, TA (TA) – rejoined from 9th AA Division by May 1941, left in June 1941 for Middle East Forces
105th HAA Regiment, RA (TA) – joined from 48 AA Bde Summer 1941; returned Autumn 1941
84th (Middlesex, London Transport) HAA Regiment, RA (TA) – joined from 49 AA Bde Summer 1941; left Winter 1941 for 6th AA Division
120th HAA Regiment, RA (TA) – formed January 1941; joined Summer 1941
132nd (M) HAA Regiment, RA (TA) –formed September 1941
156th (M) HAA Regiment, RA (TA) – formed April 1942
38 LAA Brigade – London S/L layout
26th (London Electrical Engineers) S/L Regiment, RA (TA)
35th (First Surrey Rifles) S/L Regiment, RA (TA) – to 5th AA Division Summer 1941
75th (Middlesex) S/L Regiment, RA (TA)– converted into 75th LAA Regiment February 1941 and joined 8th AA Division
79th S/L Regiment, RA (TA) – formed October 1940
63rd (Queens) S/L Regiment, RA (TA) – joined Autumn 1941 from 5th AA Division; converted into 127th (Queens) LAA Regt March 1942 and remained with brigade
48 AA Brigade– part of London IAZ
54th (City of London) HAA Regiment, RA (TA)
97th (London Scottish) HAA Regiment, RA (TA) – to 49 AA Bde Autumn 1941
105th HAA Regiment, RA (TA) – formed September 1940; to 26 AA Bde Summer 1941; returned Autumn 1941
53rd (City of London) HAA Regiment RA (TA) – rejoined from 6th AA Division February 1941; as a mobile regiment, it was part of the War Office (WO) reserve, and left in October 1941 to deploy to India
109th HAA Regiment, RA (TA) – from 49 AA Bde December 1941; to 26 AA Bde by May 1942
1st AA Z Regiment, RA – formed September 1940
14th AA Z Regiment, RA – formed September 1941
141st (M) HAA Regiment, RA (TA) – formed December 1941; to 49 AA Bde January 1942
49 AA Brigade – part of London IAZ
84th (Middlesex, London Transport) HAA Regiment, RA (TA)– to 26 AA Bde Summer 1941
109th HAA Regiment, RA (TA) – formed September 1940; to 48 AA Bde December 1941; returned June 1942
11th (City of London Yeomanry) LAA Regiment, RA (TA)– transferred to WO Reserve Summer 1941
36th LAA Regiment, RA (TA)– to 8th AA Division by May 1941
42nd LAA Regiment, RA (TA)– from 11th AA Division by May 1941
70th LAA Regiment, RA (TA) – formed January 1941
53rd (City of London) HAA Regiment – rejoined July 1940 after return from France via Gibraltar; left for 6th AA Division October 1940 (see above)
73rd LAA Regiment, RA (TA)– formed February 1941
57th (Wessex) HAA Regiment, RA, (TA) – from 5th AA Division Autumn 1941; to 11th AA Division January 1942
97th (London Scottish) HAA Regiment, RA (TA) – from 48 AA Bde Autumn 1941
141st (M) HAA Regiment, RA (TA– from 48 AA Bde January 1942
86 (HAC) HAA Regiment, RA (TA) – from 26 AA Bde February–March 1942
1st AA Divisional Mixed Signals, RCS
No 1 Company:
1 AA Command Mixed Signal Office Section
1 AA Division Mixed Signal Office Section
26 AA Brigade Signal Office Mixed Sub-Section
38 AA Brigade Signal Office Mixed Sub-Section
48 AA Brigade Signal Office Mixed Sub-Section
49 AA Brigade Signal Office Mixed Sub-Section
No 2 Company:
601 AA Gun Operations Room (Class 'D') Mixed Signal Section
315 AA Gun Operations Room (Class 'B') Mixed Signal Section
112 RAF Fighter Sector Sub-Section
5 AA Line Maintenance Section
1 AA Divisional RASC
900th and 902nd Companies
1st AA Divisional Royal Army Medical Corps (RAMC)
1st AA Divisional Workshop Company, Royal Army Ordnance Corps (RAOC) – Workshop companies became part of the new Royal Electrical and Mechanical Engineers (REME) during 1942)
1st AA Divisional Radio Maintenance Company, RAOC
1st AA Division became independent, leaving 1st AA Corps and coming directly under AA Command, during April 1942.
1 AA Division, like the other AA Corps and Divisions, was disbanded and replaced on 1 October 1942 by a new AA Group structure. London was covered by 1 AA Group.
The following officers commanded 1st AA Division:Major-General R.H.D. Thompson (15 December 1935 – 26 November 1936)
Major-General Sir Frederick Pile (27 November 1937 – 27 July 1939) – became GOC-in-C AA Command
Major-General Francis Crossman (28 July 1939 – 11 November 1940) – became GOC 2nd AA Division
Major-General Robert Whittaker (12 November 1940 – 31 December 1941) – TA officer, former commander of 26th (London) AA Bde; became Major-General General Staff, AA Command
Acting Major-General Darcy Richards (1 January–30 September 1942) – became commander of 25th Anti-Aircraft Brigade in Tunisia and Italy