Special Branch (Thames TVEuston Films crime series, 1969-74)

Four seasons of 'Special Branch' were made, spanning 1969 to 1974. Seasons one and two were mostly studio-based; three and four were more location-based action thrillers which look very like the later The Sweeney.

Episode 1.4:
London Transport AEC Routemasters provide a backdrop in a street scene.
Season 4:
Opening credits include a glimpse of Routemasters in traffic:
Episode 4.01
Views of London traffic from high up on a large building. First seen is a National Bus Company coach in National Express white coach livery - looks like Alexander Y coachwork from this angle:
Unclear what this midicoach is:
This is clearly a London Transport AEC Routemaster:
Episode 4.05
A Leyland Atlantean is used on an airport shuttle service. It's one of a batch of 5 (LLH5-9K) 1972 Leyland Atlantean PDR2/1 with Roe body new to Silverline of Hounslow, who used these buses in maroon and cream livery for the airline TWA. This bus is seen in TWA livery with a fictional 'Near East Airlines' fleetname. The registration plate is not clear, but I believe it's LLH5K, which later operated for Osbornes of Tollesbury.:
Not sure whose is the Plaxton coach in the background:
Also glimpsed is this BOAC Bedford/Duple: