The series is:
Mr. Palfrey of Westminster
It aired on ITV in 1984 - 1985. And according to IMDB it was aired in the US on PBS in the late 80s.
It was written by written by George Markstein and starred:
Alec McCowen as Mr. Palfrey
Clive Wood as Blair
Caroline Blakiston as the Co-ordinator
Briony McRoberts as Mr. Palfrey's secretary Caroline
Mr Palfrey is a mild, middle aged man—the epitome of a middle rank British Civil Servant. He is also a spook. The series is kind of like The Sandbaggers in one way and a wee bit like Tinker, Tailor, Solider, Spy, plus for some reason Mr. Palfrey reminded me somewhat of Folye.
Basically it's a very small government department, a staff of three: Mr. Palfrey, Blair and Caroline. There are no high-tech gizmos or anything like that and it focused on the more cerebral than physical aspects of the espionage business. Blair is armed and does wave his gun a few times, but in many ways it's very old-school, almost gentlemanly. They do get involved in 'dirty tricks' but when it comes down to it they are more tricky than dirty. Blair does a good line in B&E, whilst Mr. Palfrey is a master of psychology, who is clearly extremely good at his job and does the job 'his' way.
One of the quirks is that we never learn Mr. Palfrey or Blair's first names nor do we ever learn the Co-Ordinator's name (first or surname) at all; she is just 'Madam'. And the PM to whom 'Madam' 'answers' is also a female.
J and I never saw the series when it aired (and I believe it has never been reshown), but we bought the DVDs fairly recently and watched it. We thoroughly enjoyed it, yes, it may be considered a tad slow moving if you want your spy-catchers running around and being physical, but we didn't find it thus. It was excellent entertainment, a small regular cast, some excellent guest stars, intriguing plots with surprises.
Does anyone else know it?