All good things must come to an end, and so it is with Stefan Golaszewski’s tender and bittersweet comedy, with the new third series destined to be the last. Will it bring closure for Lesley Manville’s widowed Cathy as she tries to move on from bereavement to some semblance of a new life?

The first two series played out over months, as her grief was slowly explored. Fans need no telling that despite the apparently bleak starting point, laughs come from the interactions between her family of eccentrics, while Cathy’s humanity gives the comedy a firm emotional core.

For the third series the action has been accelerated – although that is a relative term for such a delicate piece as this – with the six episodes depicting consecutive days as the whole family are forced into the confines of a week away in a lavish country Airbnb that should push the putative romance between Cathy and Peter Mullan’s Michael into a conclusion.

It’s clear soon after they arrive at the mansion that their relationship has moved beyond hand-holding, but also that there is still a firm resistance to any liaison from son Jason, who clearly wants to preserve an idealised relationship with his late dad that now seems under threat. In protecting that impossibility, he can certainly be an irritant. Though there’s an extra layer to his concerns given he is about to become a father for the first time – even if his partner Kelly (Lisa McGrillis) tries very unconvincingly to hide her pregnancy and its side-effects.

Selfish as he can be, Jason is as nothing compared to Dorothy Atkinson’s Pauline, a true comedy monster so condescendingly snobbish she makes Margot Leadbetter look like Jim Royle. She is on fine form from the start, not-so-humblebragging about the luxuries of the home she’s stumped up for from the lucrative proceeds of her divorce.

While she is standoffish to the extreme, her current paramour Derek (Ross Boatman) is pathetically devoted to her, her offhandishness towards him adding a layer of poignancy to what could, in less capable hands, be a two-dimensional battleaxe. It’s clear she’s got issues of her own, while Derek is a heartbreakingly tragic creature, adoring a woman who barely gives him the time of day.

Only rarely does he give a glimpse of whatever sadness lies beneath, however – for the beauty of Golaszewski’s delicate script is what goes unsaid. The writing is economical and sometimes appears inconsequential – the entirety of episode two is based on the a single phrase describing the events of the previous night - but sparse words say so much.

A nuanced script is backed with exquisite performances, of course, especially Oscar nominee Manville carrying the piece with patience, dignity and quiet good humour. 

This looks like being a triumphant end to a marvellous comedy that will endure.

• Mum starts on BBC Two at 10pm tonight. All the episodes will be available on iPlayer immediately afterwards.