Anti-aircraft Searchlight Company, Royal Engineers?
From 1915, they were used in the London area to search for Zeppelins and other aircraft.
(T) = Territorial?
Aerial attack was a new form of warfare introduced through the advances in airship and aircraft technology. The first bombing raid on Britain took place in December 1914 when German Zeppelin airships dropped bombs in the Dover area. Thereafter Zeppelin bombing raids continued on London, as well as on locations on the East coast and on one occasion on Chester. In 1916 the Germans switched from using airships to aeroplane (Gothas).
As a consequence of the air attacks 50th Field Searchlight (FSL) Company RE was reformed in 1915 to provide searchlight anti-aircraft (AA) defence for London. The Tyne Electrical Engineers took over the running of the School of Electric Lighting, Gosport and operated it until the end of the war. By December 1915 AA searchlights units were raised as part of the Royal Engineers (TF) and deployed in the defence of industrial cities and ports throughout Britain.