This cop show about Britain's police force which fights crime with a national security angle is actually two almost completely different series, each of which ran for two seasons.
The first is a studio-made production from the late 1960s starring Derren Nesbitt (Jordan), with Wensley Pithey (Eden) and then Fulton Mackay (Inman) as his superiors, all three putting in excellent performances. Nesbitt in particular, looking immensely trendy, is magnificent, characteristically twitchy.
This Special Branch is in a state of perpetual tension with MI5, Britain's spy service, represented by the wily Moxon, who makes Machiavelli look naive. The first season contains a running thread following a failed case in the first episode, 'Troika', which puts Eden under pressure from his mysterious superiors.
The quality of script and acting of these two seasons is marvellous, but the productions mix studio-bound scenes, with the painted 'view' from Eden/Inman's window particularly obvious, with location-filmed inserts. Excellent, and very much of its time.
The third and fourth seasons are totally different under the same brand or banner, with virtually no overlap in cast with the first two seasons. These were entirely filmed by Euston, and intended to look gritty and realistic - and so it seemed at the time, but it looks a bit pedestrian in comparison with, say, The Sweeney, never mind The Wire. Compared with the first two seasons, it shifted the focus from talk to action, from internal politics to enemy action, and was much less cerebral and concerned with character. Not quite dumbed down, but the last two seasons were certainly inferior to the first two.
The star of the show was George Sewell. He had a posh sidekick, Roger Rowland who proved extremely boring (he was one of the very few cast overlaps with the first two seasons, having appeared in a small part in an early show), so while the third season was being filmed they pepped up the cast with the addition of Patrick Mower, who quickly added a bit of tension and his peculiar brand of sleazy glam.
All four seasons are available on DVD in the UK, but make sure you know what you are buying. Seasons 1 & 2 are traditional, talky and studio set, so comparable with something like the Sandbaggers (not as good, I should add, but not unlike in style). Seasons 3 & 4 are location-filmed, gritty and action-oriented, so more like The Sweeney (not as good either).
