LAST week’s small and perfectly formed mystery building was the pumping station at Greenberfield Locks on the Leeds and Liverpool Canal, on the outskirts of Barnoldswick. Michael Townson, of Barnoldswick, tells us: “The station is used to control the flow of water from the reservoir at Winterburn. “The reservoir was constructed for the sole purpose of keeping the canal at the correct level in the top pool of the canal between Barnoldswick and Barrowford. It is used in conjunction with the reservoirs at Foulridge and on white moor above Barnoldswick but the pump house only controls water from Winterburn. “