MUSIC / The secret of Humph: He's the 'comic hero' with the perfect sense of timing. He's the 'chairman's chairman'. He's the 'top trumpet man in Britain'. Martin Kelner on the busy life of Humphrey Lyttelton

Humph. Perhaps it's a noun. A humph - a wearily dismissive half- snort. Or a verb. To humph - to maintain an air of ironic detachment in the face of the frenetic efforts of those around you to be amusing.

Whatever it means, humphery is what the forthcoming new series of the radio show I'm Sorry I Haven't A Clue is full of. Regular listeners will know the form. The assembled comic turns perform some silly comedy task suggesting suitable titles, say, for the Ornithologists' Film Club. As they batter you over the head, vaudeville style, with suggestions - Nine-and-a-half Beaks, Waders of the Lost Ark, Back to the Vulture - the chairman maintains an almost audibly snooty silence until they reach some sort of crescendo. A pause. 'Is that it?' Another pause. 'Ladies and gentlemen, it's always nice to finish on a high note,' he intones languorously, 'But I can't wait, so goodbye.'

At 73, Humphrey Lyttelton, the godfather of British jazz described by Louis Armstrong as the 'top trumpet man in Britain', finds himself cast in the unlikely role of comic hero. 'He is the chairman's chairman,' says Paul Spencer, who produced I'm Sorry I Haven't A Clue for several years, and is now Controller of Comedy Programmes at Central TV. 'People like Clive Anderson and Angus Deayton have based their whole act on what Humph does.' 'His timing is superb,' says Jon Naismith, the current producer, 'I think Humph's a bit of a comic genius.'

One thing is certain. Lyttelton - forever Humph to the panellists - is the perfect foil to the public school japes and wheezes of Tim Brooke-Taylor, Graeme Garden and Willie Rushton, and the in- your-face gaggery of the old trouper Barry Cryer. At a time when BBC radio is being accused of some fairly serious miscasting - Gerry Anderson on Radio 4, Danny Baker on Radio 1, David Mellor on any network you care to mention - Humph is a reminder that the Corporation is also capable of getting the casting absolutely spot on.

He was by no means a natural choice as chairman of the improvised comedy panel game 22 years ago when it grew out of the sketch show I'm Sorry I'll Read That Again. Humph shared the chairmanship with Barry Cryer for a series before emerging, quite effortlessly as befits an old Etonian, to make the show his own. And the longer the programme continues, the more it becomes unquestionably Humph's show. In building up Humph's part - and those who have been with the show since the start will confirm this - the producers of ISIHAC have reversed the well-documented trend among comic institutions, in that it is much funnier than it used to be.

Not that Humph is about to make a career out of it. He runs his life like a piece of free-form jazz - a bit of this, closely followed by a bit of that. Band-leader, cartoonist, food writer, author, journalist, President of the Society for Italic Handwriters (Really. He learnt calligraphy from his father, a House Master at Eton, and now delights in filling in his VAT returns in perfect italic script), Humph's attitude to work is best summed up by his time at the left-wing newspaper, the Sunday Citizen:

'I was a columnist for 14 years, but I never went inside the building. Don't get involved - the secret of a long career in newspapers. I used to deliver my copy to the chap guarding the back door, and run for it.'

It was the same semi-detached Humph who wrote music reviews for the Daily Mail for four years, drew cartoons for Punch and was restaurant critic of Harpers & Queen. 'I wasn't what you would call an expert. Apparently, though, I inspired Loyd Grossman. I read an interview in which he said he thought I was the greatest living Englishman until he met Freddie Trueman. Remarkable. I only did it on the principle that by the time they found out I knew nothing about it, I probably wouldn't be doing it any more.'

The only area in which Humph is in danger of forfeiting his amateur status is the trumpet. He still practises for an hour or two each day, and when we meet for dinner at the Bull's Head in Barnes, where the seven-piece Humphrey Lyttelton Band is due to play, he gets quite serious about the menu - 'Can't order skate. There's too much glue in it - no good when you're playing the trumpet' - and drinks just one small whisky. This is some way from Charlie Parker's favoured pre-concert tipple, reputed to be two bottles of bourbon.

'You have to be a little careful as you get older,' says Humph, although his current schedule appears to concede little to the passing years. As well as presenting the long-running weekly programme, The Best of Jazz on Radio 2, Humph also fixes dates all over the country for his band - Carlisle, Edinburgh, and Abergavenny recently - and drives himself to the gigs. 'I have a Volvo,' he explains. 'I do a huge mileage in it. I got this one in 1988, and I've done 173,000 miles. The most I ever got out of one is 230,000.'

His sense of wonder in his car is mirrored by his apparent fascination with game show technology, one of several successful running gags on I'm Sorry I Haven't A Clue. 'The answer will be revealed via the megabyte magic of our giant laser display,' says Humph, as the producer holds up a piece of cardboard. The imaginary scorer, variously the pneumatic Samantha or the enigmatic Sven, is another motif familiar to addicts - 'It's nearly time to go, so while Samantha goes outside to warm up her little Morris . . .' or, more elaborately, 'Well, the last few grains of the sand of time are already slipping through the egg-timer of rate, so while I take the tops off a couple of softly boiled eggs, and Sven picks up a couple of buttered soldiers . . .'

The seamless match of script and Humph's ad-libs is a credit to producer Jon Naismith, who has introduced writers Ian Pattison and Robert Fraser Steele, who also write for The News Quiz. 'They have learned to write in Humphspeak - a sort of urbane, excessively polite, occasionally pedantic way of putting things,' says Naismith.

There's a touch of Bertie Wooster, or maybe his creator, about Humph. Like Wodehouse, he is excessively modest about his achievements. Humph's three- volume history of jazz, which he mentioned in passing, is reckoned to be some of the best writing on the subject. One more parallel with Wodehouse - and I'm sure Humph wouldn't mention it - not even a sniff of an honour, despite his towering contribution to the gaiety of nations and, incidentally, lifelong membership of the Labour Party and wartime service with the Grenadier Guards.

Sir Humph. For services to irony. In the meantime, welcome back to the funniest sound on radio: the sound of Humph humphing.

The new series of 'I'm Sorry I Haven't A Clue' begins Saturday 28 May, 12.25pm, repeated Mondays, 6.30pm

(Photograph omitted)