Brett was born in Windsor, Berkshire, the son of Oliver Sylvain Baliol Brett, 3rd Viscount Esher, and educated at Eton and New College, Oxford, where he read history.
Brett was born in Windsor, Berkshire, the son of Oliver Sylvain Baliol Brett, 3rd Viscount Esher and Antoinette Heckscher (1888-1965). He was educated at Eton and New College, Oxford, where he read history.