Created by a pair of comedy unknowns from Guernsey and featuring a fantasy island ruled by a man who tucks his jacket into his shorts and speaks a bit like Kenneth Williams (and where talent shows are judged by a dog), This Is Jinsy occupies a gentle green space somewhere between Monty Python and the Mighty Boosh, with Spike Milligan perhaps beaming his approval from beyond the grave. Add to this the fact that it goes out on Sky Atlantic – the subscription channel where even Mad Men struggles to gather enough viewers to fill Old Trafford – and it seems destined to be the very essence of a cult comedy. So why then does This Is Jinsy continue to attract such stellar guests?
In the first series there was David Tennant in snake-skin trousers as the organiser of a wedding lottery and Catherine Tate as the editor of that must-read periodical, "Glove Hygiene Monthly", as well as Harry Hill, KT Tunstall, Simon Callow and Jennifer Saunders.
In the new series, Stephen Fry, Rob Brydon, Sir Derek Jacobi and Dame Eileen Atkins are among those joining in the fun – and on the day that I visit the Wimbledon studios where This Is Jinsy is filmed, Olivia Colman, in a tweed suit and protruding false teeth, is sharing the set with a mechanical parrot. "I got the script through when I was with David Tennant on Broadchurch," she says. "And he said, 'Jinsy? Do it… do it.'"
"We have to keep pinching ourselves anyone wants to do it," says co-creator Justin Chubb. "We tried for Judi Dench and she was on a film, but most people feel quite warmly towards even if they can't do it.
"Jinsy is a combination of Guernsey and Jersey although it's more like the size of Sark," explains Chubb. "It's a Channel Island that has slipped its moorings." Chubb plays the island's incompetent despot, known as an arbiter – a figure not unlike the traditional feudal overlord of Sark, the Seigneur. "We quickly came up with the idea of people overseeing the running of an island and then it seemed logical that you'd have the person least liked or least able to run an island running it. So really it's the worst job, and that character thinks he's the most important and everyone laughing behind his back."
Another characteristic of Jinsy is that technology seems to have taken a wrong turning in around 1965. "There's a bit of futuristic technology but you're not really sure in what era it's set really… Terry Gilliam has always been a massive influence on what we've done."
Jinsy's most iconic piece of technology is the "tessallator", which looks like one of those coin-operated telescopes found at beauty spots, and which delivers electric shocks as punishment, as well as the islanders' entertainment – interludes such as "Singing Obituaries", a weather forecaster who speaks in Stanley Unwin-like gobbledygook and public information films ("'Curtain Disease' is spreading… leading to ruched necks"").
"I loved Gormenghast – the Mervyn Peake books – and we both grew up listening to Python records, watching Python, Spike Milligan… Edward Lear," says Chubb. "And Spike Jones and the City Slickers, they were very Jinsy", adds Chubb's co-star, Chris Brand, referring to the outlandish satirical musical-revue show from 1950s America. Brand plays Arbiter Maven's second-in-command, Operative Sporall. "Sergeant Wilson to his Captain Mainwaring", he says.
The duo were at school together on Guernsey, devising DIY radio programmes and shooting 8mm films with their fathers' cine-cameras and adding noises from BBC sound-effects albums, eventually singing in bands ("We used to tour Guernsey… often"). The frequent melodies on the show are their creations, including Jinsy's national anthem ("Island of silt and sand, twigs and stumps and tilth and hedgerows, fences…" ) although they think an album like the one released by Flight of the Conchords is unlikely. "All our songs are 41 seconds long," says Chubb.
While the interior sets are all filmed here in Wimbledon – the same studios where The Bill was once produced – the team return to Guernsey to pick up exterior footage. "The locals in Guernsey enjoy trying to recognise where things are," says Bran. "And there are a few little in-jokes about island's names and references to things that happened in Guernsey. We also use Guernsey surnames and places names – they have some great names." Names like Roopina Crale, Joon Boolay, Letley Orridge and Edery Molt – seen in that light, Justin Chubb and Chris Bran themselves have a certain Jinsy ring to them.
Leaving the Channel Islands, Bran attended a now defunct but inspiring-sounding media-training centre in Yorkshire, ArttsInternational, where he met This Is Jinsy's future producer James Dean. Dean was working in ITV factual programming by 2008, producing Ladette to a Lady, when he reconnected with Bran, who was now in London and writing sketches with his old Guernsey mucker Chubb. "The original idea for a show was to make a Channel Islands mock news programme," says Dean. "But then we thought that was a bit limiting and the boys came up with the idea of fictional island."
"As soon as we got the island to contain stories and characters we started making a big book full of drawings and maps and concepts," says Chubb, the trio taking a 10-minute demo to Lucy Lumsden, BBC3's head of comedy, who ordered a pilot. When Lumsden was later made Sky's first head of comedy, she commissioned Jinsy for the newly founded Sky Atlantic.
'This Is Jinsy' returns tomorrow at 10pm on Sky Atlantic