Watching an old Frost (early 90s) recently, I thought a few of the players looked familiar: the credits confirmed it. Colin Buchanan, playing the role of a uniformed constable, a bit part: he clearly had a good career, being promoted to detective inspector in Dalziel and Pascoe -- mid to late 90s-- (he was Pascoe), and Neil Dudgeon, who had been a detective inspector, but was bumped back to ' constable for a bit of biffo in the nick. He ended up a det. chief super (I think) in Midsomer Murders (2013), replacing his cousin played by John Nettles.