His name is Rip, and the cat's name is Dusty, FYI. I can't tell from his expression whether he's annoyed about being put into a suit or just idly wondering whether it mightn't be time for a nice cup of tea and some digestive biscuits.
From my uncle John, who took the photo:
I hooked a coat hanger over his collar to form shoulders, and newspaper stuffed into his trousers. Photo was taken in back garden of 4 Deerdale Road [London] in the mid-1950s.