Three additional squadrons were Canadian, and approved on the RCAF list in the late summer of 1944: No.

The squadron was formed at RAF Andover, England, on 5 March 1945, the third air observation post squadron consisting of Canadian personnel to be formed at RAF Andover, after a 1944 parliamentary debate in Ottawa, Ontario, Canada, resulted in the approval of three AOP squadrons to be added to the RCAF list, in support of the First Canadian Army.

On 7 May 1945, ten qualified Canadian AOP pilots were posted to the squadron, and from their ranks, Captain A.B.

In April, 666 began a succession of moves: on 17 April, to Alfriston Aerodrome; on 28 May, to Gilze-Rijen, the Netherlands; on 6 June, to be headquartered at Hilversum, from where the squadron's three subordinate Flights were dispersed to Dordrecht, Alkmaar, and Ede.

Tasking thereafter included VIP, Courier, and Communications Flight duties in support of the Canadian Army Occupation Force (CAOF).

666 Squadron RCAF in its turn was disbanded at Apeldoorn, the Netherlands, on 31 October 1945.