Manned by New Zealand pilots of the Royal New Zealand Air Force, but controlled by the Royal Air Force, 485(NZ) Squadron was formed on 1 March 1941 at RAF Driffield, in Yorkshire. Initially No 485 Sqn was equipped with old Spitfire Mk Is for its "working up" period in 13 Group, which was carried out with no recorded fatalities. The Spitfire Mk Is were exchanged for Spitfire Mk IIs on June 1, 1941.

By July 1941 the squadron had scored its first victories, suffered its first combat fatalities and had moved to RAF Redhill, a frontline 11 Group base to take part in offensive operations. One type of operation was fighter escort for"Circus" raids, in which a small number of RAF bombers (originally Bristol Blenheims and later Short Stirlings) were used as bait to draw up enemy fighters.

The history of the Squadron is narrated in 88 pages followed by full appendices comprising all the claims, losses (including accidental), awards, maps and the operational diary. In the third and last part, the pilots'roster gives details of the almost 210 pilots, including three Americans, one Australian, eleven British, and two Canadians, who were either posted in to or were attached to No.485 Squadron.