I'm now most grateful to someone who saw this thread and offered to look at the immigration records of sailings, given the subject's name. He has come up with the following:
Departed Southampton on 4 Jun 1957 onboard 'Liberte' of cie Gle Transatlantique, bound for New York.
Returned from Montreal, arriving Liverpool on 3 Aug 1958 onboard 'Empress of France' of Canadian Pacific Steamship Line.
So, he was only at each of the four ports once. Does anyone recognise those buildings in the background, bearing in mind that both sailings were in summer?