Westcliff MV3394, a 1931 AEC Regent with Met-Cam body and originally an AEC demonstrator, in Fairfax Drive yard in June 1951.
This (and the more or less contemporary JN961/2) were the oldest surviving Westcliff double deckers at the time I first became familiar with the company. It was probably being used on a workman's contract, a regular duty for various elderly vehicles. In the early 1950s Westcliff had a lot of this work, first transporting workmen building the Shellhaven oil refinery and later those building Tilbury Power Station.
Photo taken by Brian Pask, June 1951, Fairfax Drive, Southend