East Coast, and get off at York rather than Durham. Off the station, a (very!) short walk along a bit of the city wall, over Lendal Bridge, a quick trip round the Minster (York's cathedral - very famous for its stained glass), down Stonegate, spot of lunch / afternoon tea at Taylors Tea Rooms (or Betty's if you must) and back over the bridge to the station. 2 hours on the nose.