(BBC documentary, 1962)

Documentary about the painter John Constable.
Footage of Eastern National 400 (AVX961B), a 1964 Bristol RELH/Eastern Counties coach and numerically the first RE for Eastern Counties, carrying tourists to Flatford Mill, famed for its depiction in a Constable painting:

Unidentifiable Bedford SB/Plaxton and Ford Thames/Plaxton in the coach park at Flatford Mill:

Seen reversing is Eastern National 504 (BNO113B), a 1964 Duple Firefly bodied Bedford SB13: