Special Branch is a British television series made by Thames Television for ITV and shown between 1969 and 1974. A police drama series, the action was centred on members of the Special Branch anti-espionage and anti-terrorist department of the London Metropolitan Police. The first two series were shot mainly in a studio on videotape with filmed location inserts; a standard method of the time but one which suffered from jarring differences in picture quality between interior and exterior scenes. The location scenes of some episodes were shot on outside broadcast cameras, leading to smoother transitions between location and studio work for those episodes. Series 1 and 2 starred Derren Nesbitt as Det Insp Jordan, working to Det Supt Eden and subsequently Det Supt Inman. The episodes featuring Eden were recorded in black and white, while all subsequent episodes were recorded on colour videotape. The show was revamped in 1973 after Thames Television's Euston Films subsidiary took over production using film which allowed for a less studio-based series. Euston Films had pioneered the technique of shooting action and adventure series entirely on location using 16mm film, for a more gritty and realistic look. These episodes starred George Sewell as Chief Inspector Alan Craven and Roger Rowland as Bill North. The show was slow to take off so the producers introduced Patrick Mower as Detective Chief Inspector Tom Haggerty, and by the 1974 series Bill North had been axed, having had a nervous breakdown, though he returned for one episode later in the run.