Gritty gangster series from 1968, which I watched mainly because it was technically a spin-off from The Fellows, which was in turn a sequel/spin-off from The Man in Room 17, making this a sort of spin-off squared (although the genre of this series is nothing like the telefantasy of its predecessors). The main interest to Blakes 7 fans for whom gritty gangster series aren't really their thing may be that the series' principal antagonist was played by Richard "Nebrox" Hurndall, who it turns out was quite a versatile character actor back in the 1960s, when he wasn't impersonating William Hartnell's Doctor like his career had reduced him to by 1981-83.
Alec Spindoe (Ray "A Very British Coup" McAnally) is a former gang boss who is just getting out of prison after five years to find his London gang and his wife have been taken over by his former henchmanny Eddie Edwards (Anthony "Lacon" Bate, and nothing to do with skiing so far as I can tell) and Spindoe sets out for revenge. Hurndall plays Mackelson, a rival gang boss who wants them to destroy each other so he can easily take over their territory.
Other notable characters (and their actors) include Scaliger, a private detective played by George Sewell not long before he would go on to be in UFO, and Renata, a woman who betrays Spindoe to Mackelson (or is it the other way round?) is played by Rachel "surprise Number 2" Herbert not long after she had been in The Prisoner.
It was pretty obvious to us cats from early on that Spindoe, who is very much an anti-hero and barely more likeable than his rivals Edwards and Mackelson, was going to come to a bad end, Get Carter-style (although this was made about three years before that film was), and so the main point of interest was how, not if. The last two parts (of six) really manage to ramp up the suspense as it builds towards the climax, and this meant that the series was an interesting and worthwhile viewing experience overall.
I don't know exactly how much sex, violence or bad language they were able to get away with showing on ITV in the late 1960s, but I suspect this was towards (and maybe even pushing at, especially in terms of violence) the extreme edge for the time, though it would seem tame by today's standards. The script contains plenty of wit, but don't go in expecting a barrel of laughs.