Route 33 ran between Hounslow and Hammersmith for many years until it was replaced by an extension of route 73 in 1958. The route number 33 was then allocated to a service in east London, which operated until 1965. In 1966 the western end of route 73 (Mondays to Saturdays) became the 33 once again with an extension from Hammersmith to Kensington (Queens Gate). In 1982 the service was withdrawn between Hounslow and Twickenham and replaced by a section from Fulwell to Twickenham via Teddington.