The Danebury Metal Detecting Club is back and this time it’s serious. Well, not completely serious. Mackenzie Crook’s countryside sitcom was one of the most subtle, slow-burn comedies to pop up in recent years. There are no big laughs here, but lots of gently comic character studies to keep you hooked.

In the first episode of the new series Andy (Crook) and Lance (Toby Jones) are still out in the field looking for Saxon treasure, but tend to find junk like Tufty Club badges and old ring pulls. The fun is hearing them talk about nothing: “What a helmet,” says Lance as they discuss last night's contestants on University Challenge.

Meanwhile the calm of their hobby is disturbed. Firstly by a German visitor looking for an old WW2 plane wreck and secondly by a suggestion that the club raise funds by doing a naked calender. Neither incidents go down that well with Lance and Andy, who are pre-occupied with domestic problems. Lance is looking for romance, Andy is looking for a job and in the meantime is a house husband while his wife is the breadwinner. Wife Becky, incidentally, is played by Rachael Stirling, whose real-life mother Diana Rigg plays her formidable, non-nonsense onscreen mum.

If you wanted to be pretentious like me you could say that Detectorists is all about things under the surface. Not just Saxon coins, but masculinity in crisis, the difficulties of forming friendships and fitting in. The issues are bubbling away but never rammed down your throat. The Danebury Metal Detecting Club is a bunch of dysfunctional misfits, but they have a common bond when it comes to their hobby.

The humour never mocks these eccentrics. Well, maybe occasionally, but it is all done very gently. Crook’s script has a real heart to it. In fact in some ways it has more heart than humour and maybe this works better as a comedy drama than a conventional sitcom. But if you haven’t seen this yet it’s not too late to join this priceless programme’s fan club.

Thursdays from October 29, BBC4, 10pm.