The comedic lies invented by the panellists to win points are good, but the unbelievable truths are even better. Did you know, for example, that George Clooney used to be an insurance salesman and that Oliver Cromwell loved a practical joke?

Radio 4's long-running The Unbelievable Truth, basically an update of Call My Bluff, seems to be the exception to the panel show rule in its capacity to entertain. This isn't surprising when you consider it was devised by the same people who dreamt up I'm Sorry I Haven't a Clue. Granted, it has the same rotation of comedians - Jack Dee, Rufus Hound and Lee Mack were this week's guests - and is hosted by David Mitchell, a Stephen Fry-in-waiting who appears pathologically incapable of turning down work. But what it has going for it is an intellectual curiosity that this week turned up such invaluable facts as the radioactive properties of Brazil nuts, Florence Nightingale's love for her pet owl and Indonesia's 17 million boy scouts. The Unbelievable Truth wipes the floor with the competition. If only it could make the competition disappear altogether.

For those not aware of this show, The Unbelievable Truth is a panel game, and as is law when it comes to panel games, it involves David Mitchell.

He acts as host of "the panel game built on truth and lies", in which four comics deliver a lecture on a subject which is mostly lies, except for five pieces of unlikely true information which have to be smuggled past the rest of the panel.

In this week's edition, Tony Hawks gave a 'lecture' on mice, Arthur Smith on Sir Walter Raleigh, Rhod Gilbert on soup, and Mitchell's 10 O'Clock Live co-star Charlie Brooker on his specialist subject of television.

The show is rather like QI, in that it is partly about unlikely trivia. Among the things mentioned were the fact that Bruce Forsyth first appeared on the TV before World War Two began and that Raleigh's widow kept his severed head in a velvet bag which she carried around with her (although this fact has already been on QI).

Mind you, a lot of the lies mentioned are things you really hope are true, such as Swindon having a "Day of the mouse" in which the mice get to rule the town, or Raleigh farting during the coronation of Charles I.

My only problem with The Unbelievable Truth is that I think some of the facts might be wrong. One of the things that regularly crop up is obscure but daft American laws, like how in Nebraska you have to brew soup if you are also selling beer. I always suspect that these 'laws' are just made up and just included because they sound funny.

I've taken a while to get round to this panel game, and can hardly believe it has already embarked on its fifth series, yet it does seem curiously appropriate to our times. Whereas a format like Just a Minute relies on old-fashioned verbal fluency, the success of this show, developed by Graeme Garden, rests on the modern taste for factoids coupled with our newfound habit of subjecting everything we hear to a kind of plausibility pre-screening.

The likeable David Mitchell, who has managed in a very short time to step into Stephen Fry's commodious shoes, rules with a kind of brainy decency and surely has Radio 4 engraved on his heart. But the result is quirky rather than hilarious.

Up for discussion were beer, babies and spiders and among the diverting facts that emerged were that "most babies cry in the key of A", that Germany has a unique species of flea that is only found near beer-mats, and that Isaac Newton's only reported speech in the House of Commons as an MP was to ask someone to close the window.

Some of the alleged truths seemed a bit suspect to me, though. A spider is the only animal that sleeps on its back, for example. What about my cat, as I and a lot of other listeners protested? Then again, these truths are probably as reliable as anything else you'll hear this side of a general election.

Radio Review: The Unbelievable Truth

Everything about this Radio 4 panel show, hosted by David Mitchell, is a delight, says Elisabeth Mahoney.

A festive dollop of the panel show that encourages comedians (not that comedians need much encouragement) to twist the truth into interesting new shapes for our amusement. With David Mitchell, Stephen Fry, John Lloyd and Rob Brydon on board, this promises to be a lavish smorgasbord of skulduggery and fabrication.

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No surprise, really, to hear that Radio 4 is on a 10-year audience high, according to yesterday's Rajars. Serious times call for serious stations, but the network also has sorted out some of its weaker corners. The station's comedy - which you also need for serious times - is more reliable than it has been for years (I nearly crashed my car recently, I was laughing so hard at The Unbelievable Truth), and there are some terrific new programmes. I listen quite in awe of Americana each Sunday night.

The game show in which panellists aim to conceal truthful statements within falsehood-strewn speeches returns for its fourth series, with David Mitchell as its sardonic host. This raucous first episode was recorded at this year's Edinburgh Fringe Festival. The panellists - Rhod Gilbert, Adam Hills, Shappi Khorsandi and Reginald D Hunter - touch upon ingeniously weird topics such as whether Rudyard Kipling invented the game of snow golf (by painting his balls red so that they may be seen against the icy whiteness), and whether Edward VII had a golf bag made from an elephant's scrotum.

A new series of the panel game in which comedians read a speech on a given topic that is laden with inaccuracies, and have to smuggle three true facts past their fellow players. It always raises a smile, even if it's nowhere near as reliably funny as chairman David Mitchell's other truth-based panel game, BBC1's Would I Lie to You?