HMS PRETORIA CASTLE, a trials Escort Carrier after being converted from an armed cruiser and before that, conversion from Union Castle Liner??
There's not much to go on (but it was the same for the pilot
) and the flight deck doesn't look that wide to me to constitute a Fleet Carrier. Arrestor wire distance prop looks a little Heath Robinson as well. There appears to be either some fom of flight deck lighting on deck, but they may also be aircraft tethering points or countersunk ringbolts.
In her time, PRETORIA CASTLE carried out launch and recovery trials with almost every type of cab in the Fleet Air Arm and "Winkle" Brown was famously captured on canvas flying off a Seafire from her deck.
So I'll start the ball rolling with this submission. Probably well off the mark, but as I say, very little pictorial evidence to go on.
Wish you well in your quest.
Yarpie.