The Firechasers (1971)

Filmed as a pilot for a potential series, this movie sees Chad Everitt as Quentin Barnaby, a Fire Investigation Officer for a major insurance company, as he investigates a series of arsons.
Assisted, at first unwillingly, by investigative reporter Toby Collins, played by the very able Anjanette Comer.
Twists and turns on the way, as the pair are thrown together in an action packed plot, filled with red herrings and dead ends before the truth is realised.
An enjoyable hour and a half of popcorn munching fun, and although dated (it was a 1971 production), that dated feel also allows for a satisfying wallow in nostalgia for those who remember the London of that era.