The once frosty Caroline (Sarah Lancashire) is thoroughly thawed, having re-evaluated her life during that long and worrying night when her mum and Alan were missing.

With a spring in her step, she returns to her enviably lovely house in Harrogate to tell her nearly ex-husband John that she is in love. Though with someone else entirely. The look of horror that transfixes his face is an absolute picture (no one can do baffled comedy-appalled quite like Tony Gardner).

Things are even looking up for Alan's daughter Gillian (Nicola Walker) up there on her chilly farm in the wilds, with all sorts of unsuitable men beating a path to her door. Ends tomorrow.

Sally Wainwright's tale of an old flame rekindled after 60 years is beautifully written and acted, and it moves along at an engagingly ungeriatric clip. Following last week's adventure Alan (Derek Jacobi) and Celia (Anne Reid) are in high spirits, and events have emboldened their daughters Caroline (Sarah Lancashire) and Gillian (Nicola Walker) to move on with their lives. But then Caroline reveals her plans to her feckless husband. Fans note: the final episode is tomorrow.

Now that Alan and Celia have accidentally been shut in a stately home, their anxious families can have a long, difficult and revelatory night as they wait for news.

It's a ridiculous plot device, but at least it allows daughters Caroline and Gillian to reach an understanding as they are locked together by worry.

As for the two elderly lovebirds (Anne Reid and Derek Jacobi), they are oblivious to the ructions back in Halifax and Harrogate, and are happily planning their future together as they play cards by candlelight. Then suddenly things get all Secrets of Crickley Hall when they hear a ghost...

It feels like a turning-point episode in Sally Wainwright's drama, when we learn more about the sorrows of the past, and everyone, particularly Caroline (Sarah Lancashire), decides it's time to seize some happiness.

Aged lovebirds Celia and Alan (Anne Reid and Derek Jacobi) potter happily through their new life together as their families fall apart around them. Celia's brittle daughter Caroline (Sarah Lancashire) rages against the infuriating and inept drunken man of straw she married, while Alan's daughter Gillian (Nicola Walker) is humiliated by that nasty piece of work she's sleeping with.

This all sounds desperately soapy, but it isn't, though things get a bit weird by the end with some nonsense about a haunted country house that feels like it belongs in another drama altogether.

Still, writer Sally Wainwright likes to spring surprises (and there are quite a few of those in this episode) as Alan and Celia take the next step in their relationship. Caroline, meanwhile, drops her guard in that lovely big house in Harrogate so we glimpse the well of loneliness that lies beneath her flinty exterior.

The classy silvery romcom continues. The vicar refuses to let Celia (Anne Reid) and Alan (Derek Jacobi) marry in church - well, neither of them has attended church since 1977 - so the second-time-around lovers go in search of venues for a civil ceremony. Soon they end up trapped inside a creepy medieval mansion in a storm, telling each other ghost stories. Elsewhere Gillian (Nichola Walker) tells John (Tony Gardner) he needs to stick up for himself, prompting him to return to Harrogate and tell Caroline (Sarah Lancashire) that he's moving back in.

Celia and Alan's touching whirlwind romance has been 60 years in the making. After dropping the bombshell on their children at the end of last week's episode that they're getting married, the newly engaged couple - played by Anne Reid and Derek Jacobi - have some exciting plans to make.

Not to mention bridges to build between their daughters Caroline and Gillian, who didn't get off on the right foot. "Trailer trash" and "b****" isn't the best way to greet your prospective in-laws.

So Alan and Celia decide to throw a little ­engagement party, which, as things turn out, should at least take the heat off their romance and stop it from being the sole topic of chat for a while.

This wonderfully bittersweet comedy drama from Sally Wainwright about love among the over 70s ticks all the right boxes thanks to sympathetic writing and excellent performances with depth.

Underneath Celia's twinkling optimism and girlish delight there lies a lifetime of experience and, when she puts a patronising young salesman firmly back in his box tonight, we can see exactly where her daughter Caroline (Sarah Lancashire) gets her take-no-c**p attitude from.

One scene tonight where Caroline cuts a meddling colleague down to size makes you want to stand and cheer.

Caroline's estranged husband John (played by Tony Gardner, who also plays Professor Shales in Fresh Meat) is back in the family home, but the appearance of his other woman (Ronni Ancona) is about to rock that little boat, too.

It's not often that a TV comedy comes along that's geared towards older viewers, but Last Tango in Halifax's such a show - and it's surprisingly good.

Set in Yorkshire, the story follows two OAPs, Celia and Alan (Anne Reid and Derek Jacobi) who used to be close school-friends, but drifted apart after school, got married to different people and ended up widowed. The two then rediscovered each other on Facebook and arrange to meet up for the first time in 60 years.

Last Tango in Halifax's a comedy drama so don't expect it to be laugh a minute, because it isn't. However, what it lacks for in jokes it makes up for in surprise. The first episode, for example, sees (amongst other things) a boy getting seriously injured after falling off his motorbike and a mother accused of killing her husband.

The main plus point for Last Tango in Halifax, though, is that while you think that it's going to be very predictable, it turns out be more complicated than you think. For example, I knew that one of the characters in the show was bisexual. In the first scene one of Celia's grandsons is reading Anthony and Cleopatra and I thought, "Oh, don't tell me they made the intellectual bookworm the bisexual one, with some gushing coming out scene to his headmistress mother." But no, it turns out that the bisexual one is in fact the said headmistress mother Caroline (Sarah Lancashire), so I was certainly taken aback by that.

The other falsely-predictable moment occurs when Alan parks his car up in a car park before meeting Celia. He doesn't buy a ticket to use the car park and just walks away, leading me to think, "Oh, don't tell me that he and Celia are going to go back to the car, only to find being in the middle of being towed away or clamped." Again, I was wrong. Instead he goes back to buy the ticket, and finds some smashed up glass where his car was, as it's stolen. This in turn leads to the funniest sequence in the opening episode, where in Celia's car they discover Alan's stolen car being driven and the two go in hot pursuit of it across Skipton.

While I wasn't expecting much, it turns out that this has been a rather charming, warm, surprising programme. Certainly worth watching, considering the plot developments that occur at the end of the first episode.

Despite its charm it was difficult to see how Sally Wainwright's romantic comedy could sustain itself for another five episodes after ageing Yorkshire love-birds Alan (Derek Jacobi) and Celia (Anne Reid) announced they were getting married last week. Fear not, though, this second part proves just as engaging as the back stories of the extended families led by their put-upon daughters, headmistress Caroline (Sarah Lancashire) and farmer Gillian (Nicola Walker), develop into an entertainingly fraught family saga.

There's nothing too shocking about Last Tango in Halifax, a rather sweet and gentle love story in six parts about two elderly singletons who rekindle their romance from 60 years earlier.

Episode one features an incident of juvenile crime and a car chase, but that is about as racy as things get. Instead, the production wisely concentrates on its two leads, Derek Jacobi and Anne Reid, as they quietly go about their business of acting everyone else off the screen. Nicola Walker and Sarah Lancashire, as the couple's respective grown-up daughters, are provided with substantial subplots of their own, but it will be the incomparable Jacobi and Reid that will draw and hold the audience.

There are some titles that make my heart sink. Last Tango in Halifax (BBC1) was one of them, because I knew exactly what I was in for from the very start; a light, bitter-sweet rom-com with plenty of outdoor shots of the Yorkshire countryside to draw in the same viewers who lapped up the James Herriot vet tales. With not a hint of butter. And so it proved. Within seconds of their first appearance on screen, every character's life story was pretty much established. The widowed grandparents who used to fancy each other as kids - will they, won't they get together, what do you think? - the struggling grownup children and their dead or feckless partners, and the grandchildren making their way in the world. The only part of the first episode that took me by surprise, was Caroline's (Sarah Lancashire) lesbian dalliance with one of her teachers. Though on reflection, I should probably have seen that one coming, too.

Actually, that wasn't the only surprise. Or the biggest one, which was that despite it all being terribly familiar and predictable, Last Tango was not at all bad. It was the quality of the acting that made the show work. While I couldn't help wondering what Derek Jacobi (Alan) and Anne Reid (Celia) might have done with a more challenging script, I couldn't fault their commitment. It's not that often a pair of 70-year-olds get to take centre stage in a rom-com and they did so with charm, coyness and experience; they even managed to make the ridiculous car chase feel slightly less ridiculous. God knows how.

The rest of the cast weren't so shabby either. Both Nicola Walker (Gillian) and Sarah Lancashire have expressions that can convey a world of pain without saying a word - a distinct advantage here - helpfully glossing over most of the clunkier elements of the plot. So against my expectations, I found myself making a note to watch next week's episode. Even though I have still got a fair idea of exactly what's going to happen.