The 36th (Middlesex) Searchlight Regiment was a volunteer air defence battalion of Britain's Territorial Army (TA) from 1936 until 1961, at first as part of the Royal Engineers, later in the Royal Artillery. As part of 40th Anti-Aircraft Brigade it defended air bases in East Anglia through the Battle of Britain and the Blitz. Towards the end of 1944 the unit underwent infantry training, serving briefly in Norway at the end of the war. After the war, the 36th continued as a TA unit, with some women serving with it. In 1961, the remnants of the regiment amalgamated with others to form a combined infantry battalion, and all links with air defence were severed.

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.