After the German conquest of France the battalion was additionally tasked with attacking any paratroopers landing within the unit's area.

The regiment had its origins in a group of Independent Air Defence Companies of the Royal Engineers formed in the Home counties by the Territorial Army during 1924.

In May the first, very secret, searchlight control radar sets (SLC) began to appear, with one being stationed at a site of 468 S/L Bty operating behind Dover so that the light could pick up aircraft coming in over the Kent coast.

Home Forces became concerned about the threat from German paratroopers and AA Command's units were given anti-invasion roles.

A plan to attach groups of riflemen from the infantry training centres to 6 AA Division's widely spaced S/L sites foundered on the lack of men.

Instead the S/L detachments themselves were given the responsibility for attacking parachutists before they could organise, and spare men at company HQs were formed into mobile columns using requisitioned civilian transport to hunt them down.

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.

The regiment then supplied a cadre of experienced officers and men to 233rd S/L Training Rgt at Saighton Camp where it provided the basis for a new 548 S/L Bty formed on 16 January 1941.

[24] At New Year 1942 the regiment moved to 55 Light AA Bde in 8 AA Division, covering Plymouth and Falmouth in South West England, but 508 S/L Bty transferred to 73rd (Kent Fortress) S/L Rgt on 23 January and remained in South East England.

[1][28][29] By 1943, AA Command was being forced to release manpower for overseas service, particularly Operation Overlord (the planned Allied invasion of Normandy) and most S/L regiments lost one of their four batteries; 511 S/L Bty disbanded on 17 June 1943.

[1][31][32] In late 1944–early 1945, 314 (Independent) S/L Bty was in East Anglia, operating a line of radar-controlled searchlights from Clacton to Lowestoft engaging 'Divers' (the code name for V-1 flying bombs).

[33] By the end of 1944 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][15][16][18][38][39][40] After infantry training, 631 Regiment was sent to North West Europe in April 1945 to work under 21st Army Group and HQ SHAEF.

Regimental silver is displayed within The Army Reserve Centre, Baring Road, Grove Park, London SE12 0BH.