WOA2 you are right!
Until 1977, 873 Movement Light Sqn RE (V) had been equipped with pre-war 90 inch Carbon Arc Searchlights, as used in the Blitz, which it had used since its formation in c.1947! The old Carbon Arc Searchlights were mostly dated from 1938 and each was mounted on the back of a Bedford RL towing a pre-war 15 KVA Lister Generator trailer. As you can imagine these ‘Searchlight portee and trailer’ combinations were very unwieldy and difficult to manoeuvre in to position at night.
So during 1978 the unit re-equipped with new AN/TVS-3 30-inch Xenon Searchlights imported from the USA. The Xenons wererated at 800 Million Candle Power; more than double the power of the Carbon Arcs.
(After the Xenons arrived the old Searchlights were retained by ‘873’ for ceremonial duties including lighting up events at Wembley Stadium, Horse Guards Parade and Buckingham Palace till about 1985?)