The Queen Mary Reservoir is one of the largest of London's reservoirs located in the Staines/Sunbury area of West London within the borough of Spelthorne in Surrey. It lies south of the A308 and west of the M3 motorway. The reservoir covers and lies above the surrounding area.
The Queen Mary Sailing Club is a members sailing club on the reservoir. It owns a subsidiary company Queen Mary Sailsports, bringing all training operations "in house". The postal address for the club is in Ashford, Middlesex.