Most comedy shows don’t have canned laughter any more.

And I guess this is where the boundaries between comedy and drama have blurred somewhat.

Nothing new there then - even Only Fools and Horses with its raucous background chuckling had more than a few moments of genuine pathos.

Del sitting in the chair after Rodney’s wedding to Cassandra or holding his newborn baby up to the window, telling him how much fun they are going to have must still melt more than a few hardened hearts each night over on retro channel Gold.

But all this seems positively tame in comparison with the slew of new high concept comedies we are currently treated to.

But they aren’t really ones you can watch with the family are they ?

Back to Life, about a woman who went to prison for killing someone when she was just a teen but is trying to pick up where she left off, has made its way from BBC3, now only on line.

It is wickedly funny, but definitely not PG.

Neither are Fleabag or Ricky Gervais’ After Life, about a chap who feels suicidal after his wife dies.

I’m struggling to think of a comedy show, a funny one, which airs before the 9pm watershed.

There’s a gap in the market, but I don’t think it is going to be filled in a hurry.

Writers, even Lee Mack for the ever clever Not Going Out, want the option to stray into adult subjects.

There may be little or no swearing but I watched an episode recently with my 12-year-old which left me answering biology-based questions I would rather have avoided at that time of night.

That does actually have a live audience - so there is real laughter.

My favourite sit-com at the moment, though, is so subtle it almost doesn’t fit into any category.

In its third and, sadly, final series Mum is about everything and nothing, all at once.

Film actress Lesley Manville plays the eponymous character, Cathy, who in the first series had been recently widowed.

That series, and the second, followed her, son Jason and his girlfriend Kelly, brother Derek and his awful social climbing partner Pauline and Cathy’s former parents-in-law through a year in their lives.

It also captures a blossoming but faltering romance with her long-time friend Michael, played by Scottish actor Peter Mullan in a rare softer role he clearly relishes.

Its success is in its economy of language and seeming lack of action - almost like a fly-on-the-wall documentary.

In this third outing the action has moved from Cathy’s modest home to a country pile, hired in honour of Derek’s birthday and the series covers just a week.

Cathy’s relationship with Michael has moved up a gear - but she is too worried about upsetting others to make it official.

With good reason since her son and his grandparents are breathtakingly selfish and unable to let her move on with her life whilst they do exactly that with their own.

How this did not get nominated for more BAFTA’s, or at least win Manville the one she was nominated for will remain a mystery.

What a shame there won’t be any more of this moving, and actually very funny, series.

But maybe the Ricky Gervais approach of leaving us wanting more, stopping usually at just two series, is the right one.