Brian,
I hauled out my copy of "The Destruction of Convoy PQ 17" (New York:Simon & Schuster,1968). Irving states quite categorically that the Walrus flew off "London". As Irving quotes his sources, including the catapult officer on the "London", you would have to lean his way. What I don't understand is, Irving suggests that the pilot of the Walrus was Flight Officer H. H. Edwards (fn 43,p.314). Point taken!
The following is also known:
HMS Norfolk - Cruiser with catapult. Launched in December 1928. Survived the war.
London Gazette 26 January 1943 - For escorting a Russian convoy in July 1942.
WIGNALL, Ronald RNVR - TSubLt(A) - MiD.
Seedie's List of Fleet Air Arm Awards 1939-1969/p.65
https://www.thegazette.co.uk/London/...supplement/493
Col.