TV review: I wept like a baby in the series finale of Mum

Mum: Michael (Peter Mullan) and Cathy (Lesley Manville) - (C) Big Talk Productions (Image: WARNING: Use of this copyright image is subject to the terms of use of BBC Pictures' Digital Picture Service (BBC Pictures) a...)

JUST TELL HIM, CATHY! We've spent two gorgeous series building to the season finale, two sets of slow-burning episodes leading to fireworks night, in more ways than one – watching the unfurling of Cathy and Michael's relationship in the sublime comedy Mum has been a complete pleasure. As much as I was dreading the end of the series, I was more than paid off by the pay-off.

Having first met Cathy (the exceptional Lesley Manville) after the death of her beloved husband Pete, we have dropped in on her life over the two years that have followed the funeral.

We've seen her cope with grief, loneliness and the continued presence of son Jason (Sam Swainsbury, who has gormless off to a T) and his nice-but-dim girlfriend Kelly (Lisa McGrillis, who says as much with her face as her lines) sweary, rude inlaws Reg (Karl Johnson) and Maureen (Marlene Sidaway) and brother Derek (Ross Boatman) and his horrific girlfriend Pauline (a tour de force from Dorothy Atkinson).

We've also watched Cathy grow closer and closer to her husband's best friend Michael (Peter Mullen) in one of TV's most endearing romances of recent years.

Mum is a superb ensemble piece but Manville and Mullen are out-of-this-world as the tentative lovers who have been inching towards romance since what feels like forever – they are, of course, helped enormously by the realistic, nuanced script from the brilliant Stefan Golaszewski whose grasp of dialogue is equally stellar.

The minutiae of daily life is spelled out in Mum in a way that is rarely seen on TV: set in one house, one of the biggest roles in the show is for the wheelie bin in the front garden which is shown without fail in every episode. It's an indication of the masterful eye for everyday detail that Golaszewski has and brings to everything he writes.

This is a series about relationships with all their awkwardness, misunderstandings and affection – it's as much about the things that are left unsaid as the things that are said, although this last episode in the current series did involve a long-awaited declaration.

It was November and big changes were on the horizon: Jason and Kelly were moving to their new flat ('what we're trying to do is strike a balance between taking everything we need for the new flat and not leaving the bedroom so empty it becomes like a symbol of how lonely you are,' Kelly said to Cathy, with genuine concern) and Michael was planning to exile himself to Spain – from Thursday to Sunday every week – figuring that a future with Cathy by his side was a pipe dream.

Derek, meanwhile, was in the doghouse because he'd suggested Pauline was being a snob for castigating his purchase of 50/50 bread instead of brown, granary, 'or a French stick with seeds on it'. She wasn't, she told him, a snob, but instead just appreciated the finer things in life: '…Radio Four, Classic FM, anything made by an artisan…golf, Wimbledon, jazz, The Tate, sailing, fountain pens, skiing, cheese, seafood, wine you can't buy in a supermarket, coffee beans, manuka honey, Kent…'

Pauline's utter indifference to Derek was, however, slightly dented when she discovered his dark past after an offhand comment from Cathy about him being a loose cannon: 'I'm not proud of it…' he said, '…a little bit of arson – threw some fireworks in the Post Office and set fire to a tunnel, or tried to, took a hammer to a greenhouse. I really don't want you to think of me like that.' Pauline's eyes widened as she added 'Derek's life of crime' to her list of likes.

Reg and Maureen were complaining about everything, as usual, and refusing to move from their perma-positions on the sofa and Jason and Kelly were promising to pop home all the time once they'd moved out to have a Sunday roast, their washing done and, possibly, to eat breakfast.

Maybe it was Michael's news that he'd completed on his home in Spain, maybe it was that an empty nest was in sight, maybe it was a determination to leave behind the shy reticence, but there was a new sense of purpose about Cathy that signalled Something Important was about to be said.

Jason felt it too: over the flames of the bonfire, he reminded us that he's more than just a lazy buffoon as he warned Michael that his mother would always love his father – it's these unexpected moments that catch you out with Mum, the realisation that Jason is struggling with grief just as curmudgeonly old Reg and Maureen are: Cathy has lost a husband, they've lost a father and a son.

Finally, 23 minutes into the episode, Cathy seized her moment. In a performance where both leads said as much with their eyes as they did with words, she finally told Michael how she really felt about him, after he admitted that Jason might feel his relationship with Cathy was inappropriate.

'It crept up on me and I can't stop thinking about you…I'd love to look at you and not notice your eyes. I'd love to go to bed and not think about you,' she said, 'I adore you. Everything I think and do and say, I just want to be thinking it and doing it and saying it with you.'

I was destroyed by the loveliness of it all – Michael, on the other hand, disappeared off to the toilet to have a bit of a think about what had just happened. Just before the credits rolled, the family gathered in the garden (Reg and Maureen stayed on the sofa, but even they had a moment of tenderness, albeit one Maureen slept through) and watched the fireworks burst in the sky. As their faces lit up, Cathy reached for Michaels's hand: I've welled up even writing about it.

There are some critics who have suggested that Mum should stop right here, with the suggestion of what will happen in the future rather than the reality of what life and love have in store for Cathy and Michael, but the fact of the matter is that a third series has been commissioned and I can't be sad about that – I just hope they'll will find their happy-ever-after and that Derek isn't coerced back into a life of petty crime by Pauline.

To paraphrase the theme tune, I'm going to miss Mum while she's gone.