Founded in 1952, the school occupies a house designed by Norman Shaw at 68 Cadogan Square, and since 1994 has operated as an independent charitable trust.

The headmaster maintains links with Eton, KCS Wimbledon, St Paul's, Westminster School, and Winchester College; in any given year around 80 per cent of leavers depart for one of these institutions.

[1] Former pupils are known as Old Cadogans and include actor Daniel Radcliffe, author Edward St Aubyn, gerontologist Aubrey de Grey, and filmmaker Matthew Vaughn.

[4] Although a number of sports are on offer, such as cricket and football, Sussex House has been especially successful in fencing, and has produced more national champions than any other school in Britain.

[7] The admissions process comprises an interview and a written exam; the latter is taken in January each year and features questions on English, Maths and verbal reasoning.