Episode 1: Invasion of the Bane
A new drink is on the market, and a brightly-coloured Leyland-National is taking groups to tour the manufacturing plant. It's complete with Leyland and Leyland-National badges:
HNB24N was new as Greater Manchester PTE 105 and is preserved (in SELNEC livery) by SELNEC Preservation Society. (thanks Anthony, Phil Groocock, Matthew Aldous and Noel Baxendale)
It transpires that the plant is run by malevolent aliens, and the redoubtable Sarah Jane Smith uses the bus as a battering ram to get in!
A street glimpse of a Cardiff Dennis Dart gives a clue as to where the series was shot:
(thanks Anthony, Phil Groocock, Matthew Aldous and Noel Baxendale)