Dial 999 (ABC-ZIV police procedural, 1958-9)
The star is the American actor Robert Beattie, and it's unusual for the time in using lots of location footage, mostly in and around London. It's a good show, and worth seeing for the street scenes, which include many RTs, RTLs and RTWs.
Episode 1: The Killing Job:
London Transport RT2027 (LUC269) is seen a little too closely for comfort:
It's followed by RTL323 (KXW423) on route 22:
Southdown 1663 (NCD663), a 1954 Leyland Royal Tiger PSU1/16 with Duple body:
Episode 4: Escape:
A starring role for Valliant Tours 30LHX, a 1957 AEC Reliance/Burlingham - note there's a slight continuity glitch, the banner on the side comes and goes:
In background this appears to be a 1954 Midland Red BMMO C4 alongside a BEA RF:
Episode 5: 24 Hours:
Two roofbox RTs pass Piccadilly Circus, followed by a Leyland RTW:

Roofbox RT2166 (KGK975) on route 19:
RTW143 (KGK643) and the Scots Guards:
Episode 6: Robbery With Violence:
This Trojan is not strictly a bus, but I'll include it anyway, because it's a Trojan :
Episode 8: Missing Person:
RT family buses:
Episode 10: Special Edition:
Rickards OGT308, a 1954 Bedford SBG/Duple:
Episode 11: The Great Gold Robbery:
A blurred passing Bristol LS/Eastern Coachworks:
Episode 16: Bus 77:
The bus in question is United Counties 486 (KNV29), a 1954 Bristol LS6B/Eastern Coachworks, which appears in several scenes:
Episode 18: Heads or Tails:
Bedford SB (?) and a roofbox RT on route 358:
Episode 19: Special Branch:
Sadly it's blurred, but this is a BOAC Commer-Harrington integral coach:
Episode 21: Mechanical Watchman:
Two trolleybuses and an RT:
Episode 23: Hunter Hunted:
A London Airport scene with lots of BEA RFs in the background:
Episode 24: Extradition:
RT1745 (KYY583) on route 19, and an RTL on route 2:
Assorted RTs:
Episode 25: Honeymoon:
A coach park:
The only vehicle identifiable is a passing Bristol LS:
Episode 29: Barge Burglars:
Massed RT family buses:
Episode 31: Living Loot:
This Southdown 'decker appears to be 310 (HCD910), a 1947 all-Leyland Titan PD1A:
Episode 32: Payroll Job:
An RTL and an RTW:
RTL1033 (LLU787) is followed by RF136 (MLL523) and RTL630 (KGU80):
RT and RTL:
\\
Episode 33: Inside Job:
RT3776 (NLE883) on route 49 and RTW36 (KGK536):
Episode 35: Key Witness:
An RTL:
Scene in a toy shop:
RTW33 (KGK533) on route 31: