My wife tells me that you can no longer keep your luggage, for a few hours, in a storage room at the train station, generally, in England.
So if you're travelling from town A, where you were overnight, to town C, where you'll be overnight, with your luggage, by train, and you're changing trains in town B, where you'd like to see the sites for a few hours: What do you do with your luggage?
(To be specific, town B is Peterborough.)
(Is there, in fact, some place at a train station? Can you pay to leave it in a hotel that you're not a guest at? Or??)
(The linked question suggest doing a search for "luggage storage service" with the town in question. That turned up nothing.)