Several reviewers have moaned about this one, though one corrective comment pointed out that it was done in the Xmas Spirit. I laughed more in this one episode than in say, the entire set of series of The Office.
Helped by expert performances from Tony Melody - who could keep the same glum expression if he'd scored the winner in the Cup Final, the wonderful Michael Bates, and a little cameo from Roy Barraclough.
Plus we had Pat Heywood, as the long-suffering wife, much in demand to play similar roles over the years, being described as a sex siren at one point despite being rigged up in the sort of curlers and dressing gown that made Hilda Ogden famous!
This series is nicely about English suburban life, and the main role of private investigator gives the lead the excuse to look into many various characters and families. However, if people are really expecting to see a version of Sam Spade, or Philip Marlowe, then, as the Irish farmer said when asked to give directions, you really shouldn't be starting from here! [Oh, and I liked the episode about Mrs Podmore's cat too, but maybe you get that joke better if you have a cat?]