Awarded: June 1945
Blazon: A Mosquito proper
Link: The badge symbolises the type of aircraft used by the unit. The motto appears not to be a phrase used in classical times, but is said to be an abbreviation of a phrase used by Plato originally to describe an essential condition.
Motto: Sine qua non – Indispensible
History: Formed at Leuchars on 19 October 1942; disbanded at Wyton on 31 March 1956
Battle Honours: No Standard
Sponsored by Just Wood and dedicated to all who served with No 540 Squadron