The regulars on panel show 8 Out Of 10 Cats are to take part in a one-off special episode of daytime quiz show Countdown.

In early January, to celebrate 30 Years of Channel 4, the broadcaster is organising a night called Channel 4's Mash Up, which will see its regular hosts and presenters try their hand at other shows.

As part of the night, Jimmy Carr will present an episode of Countdown, with 8 Out Of 10 Cats team captains Sean Lock and Jon Richardson as the contestants. The Channel 4 press release teases: "Will the team get beaten by the fiendish Countdown Conundrum?"

Also during the 'Mash Up' evening Alan Carr will take part in an episode of property show Location, Location, Location. Kirstie Allsopp will teach the Chatty Man host the tricks of the property trade. Will Alan manage to negotiate a very real house purchase for a very real single girl in need of a home?

Other swaps will include Hugh Fearnley-Whittingstall being joined at River Cottage by some very surprising helpers; the stars of reality show Made In Chelsea hosting a Come Dine With Me dinner party; and Davina McCall playing an episode of Million Pound Drop herself, with the money going to charity.

Throughout the night rolling hosts will introduce each show, and there will also be comic sketches from comedians too.

Justin Gorman, Channel 4's Head of Entertainment, says that viewers can expect to see "some of Channel 4's biggest stars and some of our favourite shows as you've never seen them before. They're swapping with each other for a treat and a laugh to kick off the New Year."

8 Out Of 10 Cats is Channel 4's most successful panel show, which has been broadcasting for seven years. The show recently passed the 100 episode milestone, and regularly attracts over a million viewers. Alan Carr: Chatty Man is also a big hit for the channel, to such an extent that the network has already ordered another four series, which will keep the show on air till at least the end of 2013.

Nick Hewer, who is Alan Sugar's sidekick on The Apprentice, was today named as the new host of Countdown. He will take over from current host Jeff Stelling on the 9th January, after the episode hosted by Jimmy Carr.

Channel 4's Mash Up will not the first time Countdown has been involved in comedy. Last year the quiz took a central role to one of the episodes of The IT Crowd...