During the Second World War it defended the approaches to London in The Blitz and Operation Diver before becoming a garrison unit in the liberation of Norway.

The regiment had its origins in a group of Independent Air Defence Companies of the Royal Engineers formed in Essex by the Territorial Army in during January 1925, organised as follows:[1][2][3][4][5] Essex Group Anti-Aircraft Searchlight Companies: Recruitment was slow to begin with, and hampered by lack of accommodation.

[6][7] The Army Council considered that proper accommodation was essential to recruiting the units to full establishment, and in November the same year it gained authorisation to extend the existing infantry drill hall at Brentwood for the Essex AA Group HQ, as well as the Company HQ and one section of 311 Company.

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 Night fighters.

[27][28] The regiment supplied a cadre of experienced officers and men to 231st S/L Training Rgt at Blandford Camp where it provided the basis for a new 546 S/L Bty formed on 16 January 1941.

[37][38][39] This organisation remained in place until 1944, but by late 1943, AA Command was being forced to release manpower for overseas service, particularly Operation Overlord (the Allied invasion of Normandy) and most S/L regiments lost one of their four batteries.

The AA resources in SE England were strongly reinforced in Operation Diver, but the LAA batteries found these small, fast-moving targets hard to engage.

[40] By the end of 1944, however, the German Luftwaffe was suffering from such shortages of pilots, aircraft and fuel that serious aerial attacks on the United Kingdom could be discounted.

At the same time, 21st Army Group fighting in North West Europe was suffering a severe manpower shortage, particularly among the infantry.

[1][14][19][20][21][46][47][48] On 13 February 1945 the surplus (older or unfit) men were sent to Bursledon, near Southampton, where 82nd S/L Rgt was acting as a holding unit.