Somewhere between groan-worthy and genius, I'm Sorry I Haven't a Clue somehow feels as old as radio itself. But in fact the 'antidote to panel games' first hit the airwaves in 1972.

It grew out of the long-running sketch show I'm Sorry I'll Read That Again. With burgeoning television careers beckoning, the writers of that series: John Cleese, Jo Kendall, David Hatch, Bill Oddie, Tim Brooke-Taylor and Graeme Garden found they had little time to continue penning radio comedy.

However, Garden and Oddie were keen to continue with the medium and so looked for a format that wouldn't involve a large amount of scripted material. With the help of Hatch, they came up with an improvisational quiz show and produced a pilot.

That try-out edition opened with Garden and Kendall singing the words of 'Three Blind Mice' to the tune of 'Ol' Man River', followed by Oddie and Brooke-Taylor tacking the lyrics of 'Sing a Song of Sixpence' on to the melody of 'These Foolish Things'.

Although Garden later reflected the show had been "pretty hair-raising", it found favour with the head of Radio 4, Tony Whitby, who commissioned a full series.

Hatch suggested bringing Humphrey Lyttelton in to host, reasoning the seasoned jazz performer would be adept at improvising, and during the first year 'Humph' alternated in the role of chairman with Barry Cryer.

The Classic Clue (as it's known to its admirers) line-up was established in 1974, when Willie Rushton joined the show. By this stage, Kendall had been permanently replaced by Cryer, with Garden and Brooke-Taylor continuing from the original quartet.

Colin Sell also played a vital role, providing musical accompaniment to some of the games and providing Humph with the butt of a cheap joke: "You'll be accompanied on the piano by Colin Sell, who's playing has been the highlight of many proms... well, that and the donkey rides."

Since 1985, the show's also enjoyed great sport with the inclusion of a fictional scorer, 'the lovely Samantha' (occasionally 'the lovely Monica' or 'the lovely Sven'). Inspired by Page 3 girl Samantha Fox, she's inspired some of the filthiest double-entendres ever heard on Radio 4. 

Take this one: "In her spare time, Samantha likes nothing more than to peruse old record shops. She particularly enjoys a rewarding poke in the country section."

Games vary, but regulars include One Song to the Tune of Another, Sound Charades, Limericks, Late Arrivals and the legendary Mornington Crescent: a meaningless parody of complex strategy games.

Willie Rushton sadly passed away in 1996, to be replaced by a rotating array of jobbing comedians, including Bill Bailey, Jack Dee, Steven Fry and Harry Hill.

His absence aside, the show soldiers on, undiminished, delighting millions of listeners every year.