Imagine, if only for a moment, the horror of it. Stuck in a cell for 23 hours a day. The constant threat of violence. The grub. The toilets. The smell. My God the smell.

Then, just when a body can’t stand a minute more the door opens and in walks your new roommate - a Tory MP. Even poor Andy Dufresne in The Shawshank Redemption was spared that hell.

As it was, I thought Kevin, the “inmate” forced to share his space with Conservative MP Johnny Mercer in Banged Up (Channel 4, Tuesday), was rather gracious in the circumstances. The contract killer shared some of his career highlights, made Mercer a tuna salad, and offered him a contraband cigarette.

Admittedly Kevin had hidden the fags where the sun don’t shine and wasn’t shy about retrieving them. Mercer was so disgusted he smashed a window to let some air in. “You’re an MP and you’re getting me in trouble!” complained Kevin with some justification as prison officers rushed to the scene.

Kevin was one of a group of former inmates and prison staff selflessly offering seven famous faces a taste of “real “prison life. The big question the programme said it wanted to answer was “Does prison work?”. In reality we were here to see which celeb would crack first.

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Banged Up came with the usual caveats of such shows. How real could the experience be when “24/7 security” was in place and the celebrities were only there for less than a week?

Yet the programme did manage to get across the sheer awfulness of life in Britain’s overcrowded, underfunded prison system. The constant mayhem was exhausting to watch, never mind be in the middle of. It soon got too much for Sid Owen, “Rick-aaaaay” from EastEnders (of course they shouted it). He wanted to see what his brothers and dad, all guests of Her Maj at one point, had gone through. He looked permanently stunned.

The guy off Gogglebox - as you can see we are stretching the definition of celebrity here - looked plain frightened. “I’m going to be a bright light in a dark place,” he kept declaring as the mob gathered round. Meanwhile, Sid Owen looked as though he was about to go full Colonel Kurtz.

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Prison drama Time (BBC1, Sunday) was an altogether more sombre affair. Written by Jimmy McGovern and forming a companion piece to 2021’s Time, starring Sean Bean and Stephen Graham, it was just as excellent but perhaps twice as harrowing. Or maybe the memory is playing tricks - the first Time was hardly a canter in the park.

Tamara Lawrence, Jodie Whittaker and Bella Ramsey played Abi, Orla and Kelsey - a lifer, first-timer, and heroin addict respectively. Each with her own demons to battle, never mind their fellow inmates. It was hard to like the main trio very much but such is the strength of McGovern’s writing you did care what lay ahead for them.

More Darwinian struggles were to be had in Survivor (BBC1, Saturday-Sunday), which host Joel Dommett described as “the most physically demanding and emotionally draining game on television”. It was a ragbag of everything, from The Traitors to The Apprentice via The Weakest Link and Lord of the Flies. Survivor wasn’t fussy what it borrowed from. You had to admire the producers' sheer commitment to putting contestants through the mill. At one point they had to scrap with each other for possession of a ball - real, proper, grappling in the mud. “Drag her through the dirt!” shrieked one onlooker.

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The contestants did not disappoint in their ability to be massively annoying and entertainingly two-faced. Dommett was a hit too, being the right mix of teaser and tormentor. If there’s any justice he’s definitely getting punched before the £100k prize is claimed. There seems to be a disproportionate number of Scots judging by the accents. Is there something in the water here which makes us natural fodder for extreme game shows?

Endurance would have been a better title than Survivor, but that title had already been nabbed by the makers of the Japanese game show that Clive James made infamous and which so tickled British viewers. Oh how we used to hee-haw at the funny foreigners who would seemingly suffer any indignity to win a prize. Then I’m a Celeb and its ilk came here and the floodgates opened. Wonder if they watch Survivor in Japan?

Shetland (BBC1, Wednesday) returned, with all eyes on Ashley Jensen to see if her DI could replace Dougie Henshall’s DI as a fan favourite. The good (or bad) news is her Ruth Calder is just as miserable as his Jimmy Perez. But lurking in the wings is Jamie Sives (Guilt) as an old flame of Calder’s and Phyllis Logan (also Guilt) is once more playing a tough old broad who is not to be messed with. Made in Shetland if you like, from murders.