These days, when it comes to people who used to be on the telly, the answer to the classic newspaper question ‘Where are they now?’ tends to be a fairly predictable one: they’re still on the telly — if, that is, you look carefully enough. They’re also quite likely to be travelling abroad with a few of their peers while wearing a large hat.

The BBC started the trend — possibly even the genre — with The Real Marigold Hotel. ITV has provided the weirdest example so far, with Gone to Pot, in which the likes of Christopher Biggins and Pat Butcher from EastEnders investigated the legalisation of marijuana in California by smoking bongs and giggling a lot. Nonetheless, it’s Channel 5 that’s proving most assiduous in squeezing out cunning variations on the theme — with A Celebrity Taste of Italy, Celebrity 5 Go Motorhoming, Celebrity 5 Go in Search of Santa Claus and now Costa Del Celebrity (Friday) all featuring a bunch of fondly remembered oldies in extravagant headgear, who journey about having little prearranged adventures and, for the most part, hanging on determinedly to their well-established personas.

Sure enough, for example, in this Spanish version of the franchise, Ainsley Harriott is still unaccountably amused by almost everything, even if his smile now seems a little more frozen and his chuckles a little more effortful. Vicki Michelle from ’Allo ’Allo! remains heroically committed to being what used to be known as ‘saucy’. Anne Diamond and Nick Owen do their best to join in with the prevailing jollity, but can’t help displaying a fair amount of head-girl/head-boy swottiness.

The centrepiece of Friday’s final episode was a visit to a family-run vineyard where Vicki promised they’d be ‘getting down and dirty’. What this meant in practice is that some of them would pick grapes and others would stomp on them to get the juice. The fact that he has size 13 feet duly allowed Vicky to ask a chortling Ainsley if ‘it’s true what they say about men with big feet’ — later adding in her trusty old French accent, ‘Oo, Ainsley, you are soo naughty!’ Meanwhile, Anne was keen for us to know that ‘wine production in the Alicante region was introduced by the Phoenicians in around 1100 BC’ — and Nick that, ‘It’s thought the Romans practised grape-stomping as far back as 200 BC.’

Of course, there is something heartening about seeing these old troupers still trouping away. Even so, and for all their impressive levels of feigned excitement, Costa Del Celebrity’s resolute uneventfulness did suggest a genre now running out of whatever steam it once had. Not, mind you, that Nick saw it that way. The entire experience, he concluded, ‘has ripped me out of my comfort zone’ — which, given that he was sitting in a cosy chair beside a swimming pool at the time, must be very comfortable indeed.

As you might already have surmised, it hasn’t been a vintage week for big new shows. But at least that allows us the chance to catch up with one of the best sitcoms around. Despite being set in early 1990s Northern Ireland during the Troubles, Derry Girls (Channel 4, Thursday) confirms that the vogue in comedy has firmly moved back in favour of the unashamedly kindly, even sweet: the sort of shows — such as The Detectorists or Catastrophe — where we’re invited to like the characters a lot, and to sympathise with their flaws rather than despise them.

The central focus is on a group of Catholic schoolgirls who embody, both touchingly and very funnily, various aspects of teenage ardency — whether for drama, mischief or virtue. But surrounding them, in the shape of their families and teachers, are an unusually large number of minor characters, all supplied not only with great jokes but also with fully realised personalities from which those jokes emerge.

On Thursday, some teenagers from Chernobyl had come on a visit — as the local priest explained, ‘to give their wee lungs a clear-out’. But would they, as main character Erin feared, be overwhelmed by Derry, ‘just because of how advanced everything is here’? Oddly, it turned out that they weren’t. Instead, this fourth programme in the series marked perhaps the first time that it really began to dawn on Erin and her friends that their beloved hometown — while still fantastic, obviously — might be quite a strange place, what with all those troops on the streets and everything.

Sadly, this was also the first episode where the school’s headmistress, the fabulously cynical and world-weary Sister Michael, played only a tiny part. Happily, in her one appearance, she did get to strike a note of uncharacteristic good cheer. ‘Don’t worry yourselves too much about the whole civil-war, sectarian-conflict carry-on,’ she reassured the Ukrainian visitors. ‘There’s really only one thing you need to know: we’re the goodies.’