Bob Wingrove saw this being filmed in October 2005 and buttonholed a prop man!
"The film is called 66 and is set in 1966 when a boy has his Bar Mitzvah on the same day as the World Cup Final. The bus being used was a tatty RML (JJD---D i just didn't get the reg number in time) but it has day-glo yellow blinds for the 14
(deffo not in 66!) and to be honest it looks like they just got a bus at random. No fleet name and just looked awful."
Reviewing the footage (about thirty seconds) reveals two Routemasters, albeit not in an appropriate livery:
Also in the scene are two rarities - Dews of Somersham CUT465, a 1944 Bedford OWB with 1952 Duple Vista body:
....and Don's Coaches of Dunmow NKY161, a 1957 Yeates Europa bodied Bedford SBG