Radio 4's It's Your Round, hosted by Angus Deayton, is another show that tests the knowledge of a group of eager-to-please comics, and is so aware of its shortcomings that this week's episode began with the disclaimer: "Any similarity between this and other panel games either past or present is something we hope you don't notice." Guests are asked to think up questions based on themes of their own choosing, thus saving producers the bother of hiring writers. This week, Will Smith, the stand-up rather than the Oscar-winning actor, masterminded a series of questions about his birthplace of Jersey, while the Australian comic Celia Pacquola got fellow contestants to pitch a charity through which they might rid themselves of their greatest irritations such as flip-flops or Jennifer Aniston, with Deayton audibly arching his eyebrows throughout. For the guests on the show it was doubtless filler for their CVs; for us it was mere filler.

It's Your Round marks a radio comeback for Angus Deayton. Deayton, like [Nicholas] Parsons, is a born host, an arch, deadpan foil to contestants' excesses. The twist in this format is that guests invent their own round, and in the first episode, Rufus Hound devised "Them Next Door" in which contestants had to guess famous neighbours from a sound recording. Sex Pistols and a sewing machine made Vivienne Westwood, "Nessun Dorma" and weeping meant Gazza, and the sound of complete silence suggested Charlie Chaplin. Miles Jupp dreamt up "What Does My Dad Know?" in which contestants guessed whether his father, a church minister, would have seen Titanic, or understand what an emo was.

It was jolly and high spirited, but the threat to this game, apart from the cruel 11pm scheduling, is that it may have inbuilt obsolescence. It's Your Round promises something different each week, whereas everything we know about radio tells us that audiences like continuity. Just a Minute is Britain's longest-running quiz show for a reason. People like to know what's coming and then to have it repeated. Again and again for several years.

It's Your Round, a new late night Radio 4 quiz show where four contestants devise a round each. Presented by old hand Angus Deayton, it was a jolly listen, with most of the jolliness provided by Miles Jupp's dad, who gave the answers for Miles's round, and Rufus Hound, who has quite the most infectious chuckle on radio.

It's Your Round (Radio 4), a new panel game where contestants invent the rounds, sees Angus Deayton back presenting on the BBC, and sounding pleasingly like his old self.

So, it is all quips that embody a raised eyebrow; positive statements made, then qualified briefly and sardonically, and faux-ennui about the whole shenanigans. His sharp style works well to frame a game that is funnier in some parts than others, but always exuberantly freewheeling. My favourite game, devised by Miles Jupp, was What Does My Father Know?, with guests having to guess his father's answers to general knowledge questions. Nobody could guess, really, but hearing his recorded answers was very funny. Asked what "emo" means, he replied, bewildered, "Um, an email in Greenland?"

Angus Deayton returns to the bosom of the BBC, taking the chairman's seat for this do-it-yourself panel game in which four comedians each make up rounds of quiz questions. Sara Pascoe, for instance, invents Come to Romford. The others all compete to compose advertisements for even naffer places, like London, Woking or Loftus, an Australian suburb with a tram museum and a very dodgy parking area. Stick around for the last round, where you have to guess if short sayings are headlines or cryptic crossword clues. It's quite hard but curiously attractive.

Angus Deayton to host Radio 4 show

Former Have I Got News for You presenter to front It's Your Round, his first major radio comedy series in more than 20 years.

Sherlock Holmes himself, Benedict Cumberbatch, is the first guest host at the start of the 40th series of the much-loved comedy current affairs panel show. Here's hoping he has the right mix of affability and keen-wittedness that a good host needs, otherwise he'll be wrapped up like a Maypole by team captains Ian Hislop and Paul Merton. The show is recorded the night before transmission, so there is little that we can say, apart from doling out a few nuggets for fact-fans. Such as, did you know this is the 138th show hosted by a guest presenter in the eight years since Angus Deayton left in October 2002? No, thought not.

I'm Pete again, aren't I?" said Angus Deayton, during one of the bits of rehearsal actuality that filled out Pete and Dud: the Lost Sketches. You wish, Angus. You wish. Actually, you're Angus Deayton, which is fine as far as it goes, but still leaves a slightly conspicuous gap between towering comic genius and jobbing comedy actor.

It's a gap that would generally pass unremarked, but for the fact that Deayton, and several other contemporary comedians, had accepted the BBC's invitation to restage some Not Only... But Also sketches that the corporation, in a more careless time, had managed to wipe. If the title got you all excited at the thought that someone had found a dusty spool of film in their attic and we were going to see the real thing you will have been disappointed. This was a tribute-band celebration of Pete and Dud, rather as if someone had accidentally destroyed the acetates of St Pepper's Lonely Hearts Club Band 40-odd years ago, and they'd called in Jedward and Susan Boyle to reconstruct it from sheet music.

That analogy may be a little harsh, perhaps, but the show - one of the last things Jonathan Ross will front up for the BBC before he heads off to ITV - was an odd affair, clumsily blending the preparation for the show with a live-audience studio section in which the assembled players were introduced to do the greatest hits. Most of them, wisely, had decided not emulate the original delivery, not exactly inimitable - since the accents and manner almost instantly fed into every playground and student bar in Britain - but not easy to imitate well. That meant, though, that the focus necessarily shifted to the writing - the lines being the only residue of the original. Some of it stood up well. In one of the more famous "Dagenham dialogues", in which Pete tries to take Dud through rebirthing therapy, you could catch the authentic flavour of Peter Cook's imagination. When Dud protests at the idea that he wants to get back to his mother's womb, Pete is quick to clarify matters: "I'm not suggesting that you go around now to 465 Beckingtree Avenue and ask your mother for re-admission," he says, "It's four o'clock in the morning... and anyway it's illegal."

But in other sketches the raw words were left looking a little thin and you realised how important the volatile elements of a comedy partnership can be - the intangible stuff (including all the corpsing) - which they added to the printed words and which can only be captured by a recording. Some of the restagings here were frankly embarrassing, carrying the stale whiff of a thousand am-dram revues in which devoted fans vainly attempt to get lightning to strike twice. It was a reminder of just how good the originals could be, but not perhaps in quite the way that was first intended. "The BBC has wiped these tapes now... is that a big loss?" Jonathan Ross asked someone lamely at one point. Well if they hadn't we might have been spared this, which would have been something.

Was it madness or arrogance that persuaded the volunteers on Pete And Dud: The Lost Sketches that they could sketch in the shadow of genius? The idea of the likes of Angus Deayton and Adrian Edmondson attempting to emulate the comedy chemistry of Peter Cook and Dudley Moore seemed like the product of a lock-in after the Baftas. In other words, it should never have survived the cold light of day.

Yet, though it was light on belly laughs and clearly in thrall to its source material, Pete And Dud: The Lost Sketches was oddly entertaining. Introduced by lifelong Pete and Dud fan Jonathan Ross (and for once he seemed genuine), the set of sketches performed - 'lost' in the sense that the BBC unbelievably wiped the original TV tapes, so they only survive in audio or script form - at least served as a priceless reminder of one of the truly great comedy pairings.

It was like watching a rock tribute band who know all the words and get the notes in the right place. You could sing along but inevitably there was a spark missing. It was the brief clips of the real Pete And Dud that were worth sticking around for, the mix of surreal allusion, schoolboy smut and lady frocks making it clear how much the duo influenced everyone from The Fast Show to Little Britain.

There was a missed opportunity in the mix: Stephen Fry and David Mitchell, only featured as talking heads, would have made a perfect Pete and Dud.

Instead the originals were lovingly, though palely, imitated, new boy Jonny Sweet coming closest to catching the anarchic 1960s spirit that Pete and Dud encapsulated.

Now what we need is a series that rounds up every clip that still exists.

Jonathan Ross rounds off his BBC career this week with his final chat show on Friday, and this love-letter to comedy duo Peter Cook and Dudley Moore. Ross, a devotee of the pair's sardonic, surreal sketches, tells us that Pete and Dud were his first TV comedy love. Their series Not Only... but Also ran on BBC2 between 1965 and 1970. It will surprise no one to learn that the BBC subsequently wiped the tapes of many of its 23 episodes, some of which survive only in script form. Which is where we reach the chancy bit of Pete and Dud: the Lost Sketches. Ross's guests - including Alistair McGowan, Angus Deayton and Hugh Dennis - gather to re-create some of these vanished comedy gems. I hope it works.