51st (London) Heavy Anti-Aircraft Regiment was a volunteer air defence unit of Britain's Territorial Army from 1922 until 1955. During World War II it served in Norway, The Blitz, North Africa (when detachments defended Crete and Tobruk), and finally in Italy until the end of the war in Europe, by which time a proportion of the regiment's personnel were African soldiers, and the guns were engaging ground targets rather than aircraft.

Origin

German air raids by Zeppelin airships and Gotha bombers on London and other British cities during World War I had shown the need for strong anti-aircraft (AA) defences in any future war. When the Territorial Army (TA) was reformed in 1922 it included a number of dedicated AA units.Flight 24 Aug 1922 The senior of these was 51st (London) Anti-Aircraft Brigade, Royal Field Artillery (RFA), formed on 12 August 1922, at the Duke of York's Headquarters in Chelsea, London with 151st, 152nd and 153rd (London) AA Batteries. On 8 February 1923, it was transferred to the Royal Garrison Artillery (RGA), which had provided the AA batteries in World War I. However, on 1 June 1924, the RGA and RFA merged to become simply the Royal Artillery (RA).Frederick, pp. 754, 767.Litchfield, p. 163. The regiment formed part of 26th (London) Air Defence Brigade also headquartered at the Duke of York's Headquarters.Titles and Designations 1927. The original TA AA units were formed on a low peacetime establishment with a few old 3-inch guns on static mounts.Routledge, p. 40.

As Britain's AA defences expanded during the 1930s, higher formations became necessary, and the 26th AD Bde (now renamed 26th (London) AA Group), including 51st AA Bde, was assigned to 1st AA Division organised to cover London and the Home Counties. On 1 January 1939, the RA replaced its traditional unit designation 'Brigade' by the modern 'Regiment', and the 'AA Groups' reverted to the more usual formation title of 'Brigades'. Anti-Aircraft Command was formed in April 1939 to control all the TA's AA units and formations.

Duncan Sandys, MP, (son-in-law of Winston Churchill) was commissioned as a 2nd Lieutenant in 151st Bty in 1937.Monthly Army List various dates. In 1938, he raised issues in the House of Commons about national defence based on knowledge he had gained from his TA service. He was warned that he risked prosecution under the Official Secrets Act, but the Committee of Privileges ruled that disclosure to Parliament were not subject to the Act. This became known as the 'Duncan Sandys Affair', following which a tighter Official Secrets Act was passed in 1939.Holmes, p. 44.

World War II

When AA Command was mobilised on 28 August 1939, 51 AA Regiment was assigned to a newly formed 49th AA Bde in London, still within 1 AA Division.AA Command at Patriot Files It had the following organisation:

Regimental Headquarters (RHQ), Chelsea, London 151st (London) AA Bty, later HAA Bty 152nd (London) AA Bty, later HAA Bty 153rd (London) AA Bty, later HAA Bty

Norway In April 1940, a new 6th AA Brigade was assembled for service in the Norwegian Campaign. With the bulk of the Regular Army deployed to France in the British Expeditionary Force (BEF), the majority of the units in 6 AA Bde were TA units withdrawn from AA Command, including 51st AA Rgt. These units had to be brought up to war establishment and provided with equipment for mobile warfare. 51 Rgt had 23 3.7-inch guns (out of an establishment of 24), but all the units were short of men and vehicles, and had to make do with some ad hoc arrangements.Routledge, pp. 109–12.Routledge, p. 373.Derry, Appendix B, p. 267.Joslen, p. 461.

For the projected attack on Narvik by Lt-Gen Claude Auchinleck's North Western Expeditionary Force in May, AA guns were landed at Harstad, an island base just outside Narvikfjord with an anchorage, and an airstrip in Skånland Municipality on the opposite coast. 151 and 152 Batteries were among the AA troops deployed to defend these positions, while other units of 6 AA Bde went to defend the RAF's airfields and provide cover for the advancing British and Allied troops. 153 Bty and its eight guns were embarked to cover a blocking force based at Bodø, but never sailed.Derry p. 201.

6 AA Bde did not start to arrive until 6 May: 'As it came into action its guns were engaging enemy aircraft almost daily as aerial attacks were made in shipping in the fjord. 152nd Battery reports firing barrages and on one occasion firing for four hours without stopping'.Farndale, p. 27. With high mountains and low cloud, early warning coverage was poor, with just a single RAF radar post on the Lofoten Islands, and the Army AA had to rely on radar-equipped warships, which provided most of the AA cover in Narvikfjord. Nevertheless, the guns claimed a number of enemy aircraft destroyed. Narvik was captured on 28 May, but immediately afterwards orders were received to destroy the port and evacuate to the UK. (The BEF was simultaneously being evacuated from Dunkirk).

To cover the evacuation, AA units were ordered to maintain maximum activity and especially to prevent reconnaissance overflights. At the same time, 6th AA Bde was ordered by London to recover its guns as a matter of priority. This was done by progressively thinning out defences. Although much of the force's equipment was saved, the AA guns were kept in action until the last minute to cover the evacuation, and many had to be abandoned. 6th AA Bde was able to save five 3.7-inch guns at Hardstad, with a number of predictors and heightfinders. The brigade ended all AA defence on 6 June and by 8 June the British troops had embarked with their surviving equipment and the convoy sailed for the UK, still under air attack.Derry, pp. 220–2.

The Blitz

The returning AA units were rapidly reinforced, re-equipped where possible, and redeployed for future integration into existing defence plans. 51st HAA, with 151, 152 and 153 Btys under command, went to Troon where it re-equipped with 3.7-inch guns.Farndale, p. 98. On 1 June 1940, along with other AA units equipped with the older 3-inch and newer 3.7-inch AA guns, it was designated a Heavy AA (HAA) regiment.

During the Battle of Britain and the early part of The Blitz 51st HAA served in 48th AA Bde responsible for the air defence of London.

North Africa The regiment left the UK again in late 1940 and sailed to Egypt under the command of Lt-Col Murray McIntyre. The Italian offensive into Cyrenaica had begun on 13 September, preceded by air attacks, and although the Italians halted after just two days, it was clear that the Western Desert Force (WDF) required more AA cover. 51st HAA Rgt reached Cairo on 16 October 1940 and came under the command of 4th AA Bde, assembling in the rear area ready to move up in the mobile role to support the WDF.Farndale, pp. 126–30.

151 Battery was sent onwards to Crete, while RHQ, 152 and 153 Batteries each with eight 3.7-inch guns reached the front line at Mersa Matruh by 21 November. After the WDF had defeated the Italians in December 1940 (Operation Compass), 51st HAA followed the advancing troops, being brought up to strength by the addition of 16 Bty from 2nd HAA Rgt. 153 Bty was temporarily attached to 7th Armoured Division from 1 January 1941, until it returned to Egypt to refit. Unfortunately, the situation in the Greek Campaign deteriorated and, on 16 February, 2nd Bty was recalled from Benghazi and had to drive back 736 miles to Egypt to embark for Greece. 51st HAA Regiment reached the British forward base at Tobruk with only two batteries.Joslen, pp. 478 & 481.Routledge, pp. 128–29.Farndale, pp. 126–30, 136.

Crete Before the German invasion of Crete began in May 1941, 151 (London) Battery was deployed with one Troop at the naval base of Suda and the other at the airbase at Maleme. The bases had been regularly dive-bombed in March and April, and the HAA guns at Suda had to be reorganised for close defence against these tactics. In May the Luftwaffe began attacking the AA sites directly. When the German airborne assault began on 20 May, some of the paratroopers were specifically tasked with knocking out the AA defences. The troop of 151 Bty at Suda had two 3.7-inch guns knocked out by mortars and the gun detachments were caught up in firefights and overrun. Although German casualties in men and aircraft had been heavy, more than half the AA guns at Maleme were knocked out, and the following day German troop transports were able to use the airfield. On 26 May, the Allied forces were ordered to retreat, the remaining AA positions were ordered to destroy their equipment and move by small boats or cross-country for evacuation from the south coast of the island. Many could not be evacuated and became prisoners of war. 151 (London) Battery was so reduced that shortly after the survivors reached Egypt GHQ Middle East ordered its disbandment, which was carried out on 1 July.Creforce at British & Commonwealth Orders of BattlePlayfair, Chapter 7.Routledge, pp. 148–52.Farndale, pp. 179–81.GHQ ME 28 June 1941; copy in 580th (Lancashire) Army Troops Company, Royal Engineers, War Diary 1941, The National Archives (TNA), Kew, file WO 169/1914.

Tobruk

On arrival at Tobruk, 51 HAA's workshop detachment set about restoring some of the captured Italian AA guns to working order, while the two batteries followed the WDF to Benghazi. But when German intervention turned the campaign in early 1941, the batteries were recalled, retiring through Derna to Tobruk, in action much of the way. By 7 April, the whole regiment (less four guns still withdrawing from Gazala) was within the Tobruk perimeter.Farndale, p. 160-2. The German breakthrough bypassed the port, which was invested from 11 April, beginning the epic Siege of Tobruk lasting 240 days. 4th AA Brigade was a major element of the garrison, and had been reinforced just before the ring closed round Tobruk, with 235 (Kent) Battery of 89th (Cinque Ports) HAA Regiment arriving to replace 151 Bty. Eight static 3.7-inch guns had also been delivered by sea, making a total of 24 guns available (although two were disabled early in the siege by premature bursts), and 152 and 235 Batteries each had an Italian 102mm gun in addition. On 14 April, Regimental HQ and 153 Bty were attacked by Stukas; Lt-Col McIntyre was among those wounded, and later that day RHQ was evacuated by sea to Alexandria. Thereafter, 152, 153 and 235 HAA Batteries, together with 51st HAA Regiment's workshops and signals, formed part of the Harbour Defended Area under the command of HQ 13th LAA Regiment.Routledge, pp. 129–30, Table XX, p. 141.Farndale, pp. 165–7.