Jack Seale

A big guest straight off the bat for series four: Andy Murray, taking a break from tantalising losses in Grand Slam semis. In the last series, Tim Henman fired serves at the show's regulars. How can Murray top that? By picking up a microphone to reveal his talent for rapping, backed by regular host James Corden.

The show's also held onto star players John Bishop and Andrew Flintoff, along with Jamie Redknapp and Georgie Thompson. Other guests are comic Jason Manford, and Southampton legend Matt Le Tissier.

The music quiz returns for a 25th series with an unsafe pair of hands at the tiller: fresh from baffling the nation as a judge on Britain's Got Talent, David Hasselhoff is your host. Bracing themselves to laugh uncomfortably as the Hoff delivers jokes he doesn't get to a spot six inches to the right of the camera are regular captains Phill Jupitus and Noel Fielding.

Among tonight's guests are replacement Sugababe Amelle Berrabah, chronic jazz-hander Louie Spence and comedian Peter Serafinowicz.

It should be a proud moment for Arbiter Maven, as construction of the fourth wonder of Jinsy, a bridge built in the shape of Maven's nose, reaches the halfway point. But that's as far as it'll ever go if local environmentalist Edery Molt (a typically excellent Kevin Eldon) gets his way. Can Maven bribe him with a rare bat? Why is Sporall turning orange?

The main story is joyous enough - when Maven gets Molt round for dinner, there's a fantastic visual gag that literally has another, even better one hiding behind it - but as always it's the irrelevant inserts that make This Is Jinsy the bulging, shop-soiled selection box it is. Tonight, bits I rewound and played again included a bulletin from half-dead reporter Jesric Underdone (this week's top story: using live rats as cavity wall insulation), and an insane contribution from the jumpily edited, Stanley Unwin-esque weatherman Tracee Henge.

Best of all is KT Tunstall guesting as throaty shanty-man Briiian Rattagan. His/her song is utter nonsense but catchier than a burr cardie. Altogether now! "It's cold and it's wet and it looks just like an onion..."

On the eve of the island's beard-growing contest, hairy chins on Jinsy are suffering random attacks from a phantom nibbler. Arbiter Maven (Justin Chubb) is no help: he's busy trying to get on the cover of Glove Hygiene Monthly by wooing its maniacally pristine editor, Roopina Crale (Catherine Tate). They have a series of tensely erotic encounters ("Mmm, you smell of... nothing"), but clean freaks and beards don't mix.

Resident psychedelic folkster Melody Lane (Chubb in a paisley dress) provides a disturbing, catchy song about hygiene, in one of the many lovingly crafted inserts that enhance the action and repay repeat viewing. This Is Jinsy has solid comic chops beneath its obscure exterior.

The creator of top Radio 4 sitcom Cabin Pressure has his own sketch show. It's head, shoulders and some of the torso above most radio comedy: every sketch is a clever idea neatly executed, with tricksy wordplay and dazzling ideas that never tip over into smugness because they're just too funny. Among the highlights are an intervention staged by friends of chronic honey addict Pooh, and a terrific takedown of asinine "things to do before you're 30" books.

Doc Martin is an admirably consistent character. It must be very tempting for the show's writers to soften him, but they realised long ago that he's funnier if they don't. At the start of the new, fifth series, we've seen Martin bereaved: a couple of misty moments are all he's allowed himself before reverting to brusque medical advice. Thus the second episode opens with Martin at a funeral, being rude to people who offer him condolences and devoting his entire eulogy to the science of cardiovascular disease. It's a daringly silly comic set piece.

Imagine Terry Gilliam and the Zucker brothers co-directing a remake of The Wicker Man starring Stanley Unwin and Flight of the Conchords. You're now about a seventh of the way to appreciating the silly, knobbly magic of This Is Jinsy. It's a secret club you must join.

Set on the musty, muddy-brown island of Jinsy, it stars its previously unknown writers Justin Chubb and Chris Bran as Maven, the community's fussing "arbiter", and his sensible sidekick Sporall. They're a classic sitcom duo but little else is familiar in this bumper hamper of visual gags, twisted characters and fantastic parodies of 1960s folk-pop.

The opening double bill features David Tennant as a flamboyant game show host, and Peter Serafinowicz as a cupboard salesman.

This Is Jinsy. Welcome...

How two unknowns created one of the year's best comedies - and why most people won't see it.

Ruth Jones dips her toe into chat, something she's done before at Christmas and Easter. Let's hope it doesn't become more than a seasonal sideline: this show is 40 minutes of pleasing fluff, but I'd swap it for four minutes of her writing or acting.

First onto the cheery, retro sofa is Sarah Millican, who's a trusted guest because she's inoffensive without being bland. She gets away with discussing her attraction to gorillas while still seeming cuddly and safe. Animal-based innuendo becomes a theme thanks to Jonathan Ross, who's less cuddly but as always has a lot of wit behind the smut. Episodes star Stephen Mangan arrives last, offering a random but funny anecdote about an Israeli immigration official.

It all feels like an unfinished pilot, or a dream about a 1970s chat show with modern guests.

BBC3's Edinburgh Fringe coverage peaks with this, their own live comedy show recorded two days ago at the Edinburgh Festival Theatre, held in aid of a local charity that provides support to people with HIV and hepatitis C.

It's just about the closest you'll get on the TV to the cream of the Fringe. Dependably funny
big names are everywhere, starting with the two comperes: Jon Richardson, who's been bringing his diffident wit to Eight Out of Ten Cats this year, and the smart Andi Osho, who should be a bigger TV property than she is. On the bill are Ed Byrne, Mark Watson, Shappi Khorsandi and Seann Walsh, among others.