. . . trousers.
Actually they are in the seaside town of Bournemouth and most likely on their way from the hotel or one of the beach huts to the beach. It's the early 1930s, the signs which can be seen inform us that the speed limit is 8 (miles per hour) and 'CARS NOT ALLOWED TO PARK HERE', so it's obviously before the advent of double yellow lines. From a couple of other shots I have of the same stretch of front, it looks like parking spaces on the other side of the street were pretty hard to come by.
Of course this had me googling to find when double yellow lines were first used to indicate no parking, I found this page on wiki saying they were part of the 1960 Road Traffic Act, and another mention that a yellow line (maybe not double) used to indicate no parking appeared in Slough in 1956.