Aidan Smith's TV week: The Castaways (Paramount+), Death in Paradise (BBC1), Men Up (BBC1), Ricky Gervais: Armageddon (Netflix)

It changes in an instant. One minute TV’s recurring image is of home, everyone round the tree or snug on the sofa - tired, stuffed, down to the hard toffees and in the bleak midwinter definitely not going anywhere.

Sheridan Smith is lost on a desert island in The Castaways

The next we’re encouraged to fantasise about definitely going somewhere. Blue skies, blazing sun and suddenly, from having to loosen top buttons, it’s beach bods. The kids are on the flumes and we’re in the infinity pool sipping brightly-coloured drinks. Christmas is over and the commercials are relentlessly plugging summer holidays.

Half-shut your eyes and so are the immediate post-Yule dramas. The Castaways (Paramount+) has an unspoilt island, shimmering white sand, exotic wildlife. Lovely. Except the plane which brought Sheridan Smith here crash-landed and so won’t be taking her back home. And by “unspoilt” I mean completely bloody deserted. And by “exotic wildlife” I mean salt-water crocodiles.

Smith is Lori Holme and she’s not alone on this South Pacific pimple. There’s The Grizzled Pilot. The Priggish Businessman. The Yummy Mummy. The Kind Psychiatrist. The Damaged Ex-Squaddie Constantly Sharpening His Knife On A Rock. And, yes, I know what you’re thinking …

Doon Mackichan in Death in Paradise.

This is like one of those 1970s disaster movies. Disparate, desperate folks in a group-jeopardy thriller. Who’s going to be the leader? Who’s going to be the hero? Who’s going to be the villain? Who’s going to get off with who for one last frantic, doomed coupling? And who’s going to die first?

I’m into this. It’s shlocky but I loved Airport, The Towering Inferno, The Poseidon Adventure and the rest and I love Celine Buckens who’s Lori’s sister Erin in a classic Hanoi Jane feather-cut, refusing to believe she’s dead and, some years after the plane’s disappearance, is attempting to find out what happened.

Lori’s role is that other hoary staple of the disaster movie: The Woman Who’s Come Away To Forget. Her husband’s been cheating on her and now his lover is pregnant. As it jumps between the sisters’ timelines, the fiver-parter flashes up “NOW” and “THEN”, in case we get confused.

Of course these disaster movies stood or fell by the quality of their special effects. If the tall building was standing and then suddenly falling it had to look real, something Charlton Heston’s Earthquake achieved by fitting out cinemas with Sensurround to make the earth move. Some of you will have souped-up speaker systems for your TV experience; I don’t and so when The Castaways’ plane is being tossed around in the tropical storm it just seems as if the director has shoogled the camera a bit. The croc, though, looks pretty convincing.

The Viagra trials guinea pigs hope for a stimulating experience in Men Up.

Will the earth move for Lori? She gets close to The Damaged Ex-Squaddie Constantly Sharpening His Knife On A Rock after he saves her from drowning while attempting to retrieve a big wooden box from a cargo ship which had washed up on the rocks. “Please let it be food,” she says. It’s hair-dryers, loads of them.

In front of that crackling fire, Death in Paradise (BBC1) keeps us wriggling our toes in one of Billy Connolly’s big slippers while wishing there was sand between them. The Castaways’ tropical setting is so tiny it doesn’t have a name but this is Saint Marie, the most famous - fictional - island on TV. There have been 12 series and no sign yet of the gentle murders abating, or of DI Neville Parker (Ralf Little) taking any less than a very leisurely and extremely clunky hour and a half to solve the crime.

Indeed Death in Paradise is now a franchise known as the “Paraverse” with one spin-off, Beyond Paradise, getting a Christmas special of its own and another, the Australia-set Return to Paradise, commencing filming next year. How has this happened?

The stories are all the same. No one ever says anything witty or profound. The acting varies from flat, as if the heat down in the Caribbean has got to the performers, to excitable, as if the rum has. Every scene ends with someone aiming a mildly suspicious glance in the direction of the person who’s just walked away. There are many more red herrings in the plots as there are red snappers on the beachside grills.

But maybe all of this is Death in Paradise’s weird brilliance: by never getting too clever or too complex or too slick, we can all feel pleased at having more or less cracked the case before the closing exposition and the big reveal - even the most reluctant armchair sleuths (me) and even the most dim-witted (me again).

As always there are guest stars. Patsy Kensit, bless her, doesn’t seem to know what’s happening and wears the same frozen expression throughout the investigation into how the entrepreneur ended up dead in a ravine. Doon Mackichan plays Neville’s mum as almost a cousin of Cathy from Two Doors Down - just as embarrassing and and just as sex-mad.

Which brings me neatly to Men Up (BBC1) where there’s plenty of embarrassment and everyone has sex on the brain, only it’s just not happening.

Matthew Barry’s drama is based on the true story of a group of middle-aged men in Swansea who in 1994 took part in trials for a new impotency drug which was launched four years later as Viagra.

No wonder Meurig shrivels up from wanting to discuss his problem with wife Ffion. The opening scene has him visiting a therapist (“Found her in the back of a girlie mag”) who insists on calling him Martin and suggests he gives his penis a name so they can commence earnest discussions. She reels off possible remedies - inflatable rods, pumps, injections, suppositories inserted … you don’t want to know - and he bolts for the door.

Then there’s Colin, a widower, who phones up a woman from lonely hearts for flirty crossword fun but his anxiety over what she might expect if they ever met seems well-founded (Him: “Five across: swollen, or becoming swollen … ? Her: “Tumescent! I’ve always loved that word.”).

Peetham, meanwhile, is intimidated by the size of the marital aids brandished at his wife’s Ann Summers parties. Eddie displays the most bravado and cracks a lot of jokes (“Soft as Mr Whippy in June”). Tommy has to hide being gay to sneak onto the trials. Men Up is funny and touching, not least in the bond which develops between the men, for the pills don’t work for all of them. But the lucky ones feel like breaking into song and this actually happens in a terrific dance number, roping in nurses, a passing brass band and some binmen.

Finally, Ricky Gervais: Armageddon (Netflix) in which the comedian announces he’s gone woke and then, over the course of an hour of the usual provocative, clever, outrageous, excoriating, did-he-just-say-that? stand-up, has a laugh at the expense of Taylor Swift, James Corden, Greta Thunberg and Gary Lineker, but mainly all those people who’re at pains to stress how woke they are. You might be shocked; I laughed a lot. This is one of the few gags I can get away with repeating: “No one needs a white, middle-aged man anymore - unless your boiler’s broke.”