(1961, David McCallum, Jill Ireland, Kenneth Cope) Opening sequence shows a journey by London bus at night. Two RT family buses are seen loading:

RTL766 (KYY736) is seen in traffic on route 12; at one point an RF passes in the other direction (these screencaps considerably lightened!):

However the RTL then seen unloading passengers (albeit also on route 12) is RTL414 (KLB601); a Routemaster on route 88 stops behind it.