Ruislip Lido ( ) is a reservoir and artificial beach in Ruislip, within the London Borough of Hillingdon, England, situated between Ruislip Common, Ruislip Woods (a Site of Special Scientific Interest), and Poor's Field. Originally created as a feeder basin for the Grand Junction Canal in 1811, the reservoir was reopened in 1933 as a lido, with facilities for swimming and boating. During the Second World War, the lido was secretly used by the Royal Air Force to train aircrew based at RAF Northolt and RAF Uxbridge in water survival methods. A narrow gauge railway, the Ruislip Lido Railway was opened in 1945, and now runs about two thirds of the distance around the reservoir. Having fallen into a state of disrepair during the 1970s and 1980s, the lido has since undergone renewal works, and was the subject of an enhancement project unveiled by the London Borough of Hillingdon in January 2010. The project involved the return of boating and swimming in the reservoir, which had previously not been possible due to pollution and an artificially low water level. History Construction The Grand Junction Canal Company purchased of Park Wood from King's College, Cambridge, of land from the commissioners, and of the cottages and gardens of the hamlet of Park Hearne. The valley that the land covered was then dammed and flooded. Engineer John Rennie and constructor Hugh Mackintosh opened the reservoir on 5 December 1811 as one of the feeders for the Grand Junction Canal. Because the water became polluted by residues from the flooded land, the reservoir did not fulfil its intended purpose, and its role as a feeder ceased in 1851. The canal (now renamed the Grand Union Canal) is to the west of the basin, so a culvert was built to lead water into the canal at Hayes Bridge. Some of the route was underground and parts have been built over. Part of the route includes a little-known aqueduct which carries the canal feeder over the River Pinn near Woodville Gardens. Lido opening The reservoir was developed as a lido in 1933, with an Art Deco-style main building designed by George W. Smith, together with an area reserved for swimming. The formal opening was by Earl Howe in 1936. The building included a cafe and changing rooms, and featured a terrace with steps leading into the enclosed swimming pool. The pool was built with a concrete