Well, thanks very much to everyone who replied!
In fact I made an error in my original message - it was 17 Railway Terrace, and not 'cottages' - I got it mixed up with Railway Cottage which was in Alma Street.
In the 1970s we spent a rainy evening driving around Sutton, looking for an area my mum vaguely remembered being called 'Pudding Bank'. An elderly Policeman told us that he was probably one of the few people in Sutton to know that it was actually Pudding in't Bag, all gone by then, of course.
And there it is, on the Sutton Beauty & Heritage website - a map of Pudding Bag, with Railway Terrace and Church Street - Thanks again
Nick