I'd suggest it's F/O braid, and lower flat button (exposed below belt) and St Edward's (Queens) crown clearly indicate post-1952.
Blues and brown gloves may indicate northern hemisphere.
Lack of wings indicate pre-flying training.
Background doesn't look like Valletta or anywhere en-route to southern Africa but does look reminiscent of a colonial Naval yard. Doesn't remind me of Liverpool either so possibly not a departure.
From the details provided I'd therefore suggest a completely un-educated plump of an age 21 (post-uni graduation) deferred National Service pilot trainee candidate for the NATO Flying Training Course arriving at Halifax, Nova Scotia c.1954-55; perhaps aboard the Empress of Scotland or similar and moored either in the river or at Dartmouth/Alderney landing?
Just a suggestion to stimulate the debate - happy to stand corrected by those closer to the truth!
And to add to 212man's example- William Woollard (of original Top Gear fame) was also a NS pilot; who undertook the NFTC in Canada. (In his case, pre-University, so as an Acting P/O and at age 18.)