It is 475 acres (1.92 km2) in size or about 1 km in diameter - making it one of the largest inland areas of water in Southern England.

This is one of a number of reservoirs to the west of London and was completed in 1976.

[3] The water improves in quality during its retention in the reservoir as solids settle and organic contaminants are adsorbed and degraded through a combination of natural biological processes aided by sunlight and oxygenation.

[5] During the design and early construction it was called the Datchet reservoir due to its closeness to the town.

[6] Engineering design data for the Queen Mother reservoir is as follows.