The show was revamped in 1973 after Thames Television's Euston Films Limited subsidiary took over production using film which allowed for a less studio based series. These episodes starred George Sewell and Roger Rowland. The show was slow to take off so the producers introduced Patrick Mower, and by the 1974 series Roger Rowland had been axed, his character being shown as having a nervous breakdown (though he returned for one episode, later in the run).
Another character was Strand, the man from the ministry, played by Paul Eddington. Strand was a toffee-nosed civil servant who kept an unwanted eye on the detectives and their budgets. He sometimes manipulated them in order to pursue obscure matters of state, such as in "Double Exposure".
The 1973/4 series of this police drama is notable for being the first production by Euston Films, later responsible for such series as The Sweeney and Minder. The influence on The Sweeney is clear, although the rough and tumble nature of that show is fairly lacking in Special Branch.
The 1973 and 1974 series have been released onto DVD by Network, and both sets include an episode from the original Thames TV series. The 1969 series was released as a 4-Disc DVD set by Network in January 2007 and the 1970 series was released as a Website Exclusive in November 2007.