Vivienne - there is an article "Lanes, Alleys and Quays of old Sunderland", by C B Walker in 'Sunderland's History', Vol 5 published by the Sunderland Antiquarian Society in 1989. In there it says: "Bull Open see PLumbers Alley, Silver St." and then: "Plumbers Alley/Chare 6 Silver Street." Alan Vickers.