The Secret Life of the National Grid (BBC documentary series, 2011)

Fascinating look at what sounds like a boring subject: the history of the UK's national electricity supply network, and the power sources that have supplied it.
Episode 1:
Footage of trams and motor and horse buses in London:

Episode 3:
Albeit distorted, there is nice footage of Lockey's of Bishop Auckland JXN371, originally London Transport RTL48, in use as a works bus - the footage is also used in the 2012 documentary The 70s:
A row of works buses at a nuclear power station site:
A stylised American school bus:
....and footage of the miners' strike features lines of Lex-bodied Metropolitan Police Bedford VAS buses: