Edinburgh Festival: The master of chorus masters: The man at the back - Arthur Oldham, for 30 years master of the Edinburgh Festival Chorus - is bowing out. Sabine Durrant talked to him before his final performances

Last week the Edinburgh Festival Chorus performed Mahler's Symphony No 8 to an ecstatic reception: 'A glorious meal of it', noted the Guardian. 'Probably one of the best choruses in the world', swooned the Independent.

Arthur Oldham, 'one of the finest choir- trainers of the century' (the Times), rubs his hands after reading the papers and looks down at the ground. 'Most embarrassing,' he says. 'Most kind.'

This combination of humility and pride seems typical of Oldham, a man who describes himself as 'an instrument-maker' but who will gleefully tell you tales of the occasions he outwitted the conductor. But this is a particularly emotional moment for him. Thirty years after he founded the chorus to sing Mahler 8, in 1965 (with only nine years truancy to the Amsterdam Concertgebouw since) he has decided it's time to leave it.

He and his wife live in France - where he's chorus master for the Orchestre de Paris - and the weekly Monday to Tuesday trip, Charles de Gaulle to Edinburgh, has got to his shoulders: 'It's arthritis, ' he says, stroking the top of his big yellowing beard into little peaks, 'from the plane. I thought I'd give it one more year, but it's just got too much.'

Oldham is sitting next door to the Festival press office, an unruly man tidied into various shades of fawn (tweed jacket, slacks, matching shoes), with a team of PRs and a packet of John Players at his fingertips. He's clearly rushed off his slip-ons what with all the rehearsals and the recreational activity ('I think of the festival as a golfing holiday interrupted by concerts'), but get him on the subject of his work, he says, and he'll talk for hours. 'I'm alive then, you see.'

A penniless orphan from Surrey, Oldham won a composition scholarship to the Royal College of Music at the age of 16, became a private apprentice of Britten ('If you look at the original manuscripts of Peter Grimes, they're my bar lines]') at 19 and was rapidly becoming the grand old man of the chorus world at 26.

At one point, he had four choirs on the go at the same time. 'It's fascinating how different a group of voices can be,' he says. 'With both the French and the Scottish choirs, whatever you do at the rehearsal they will do better at the concert, there's always something extra, whereas the Dutch choir, the Concertgebouw, will do no more and no less. I can depend on them; I can attend the first concert and go back to Paris knowing they'll be perfectly safe for the following five. But my people in Paris and Edinburgh, if I'm not in the hall . . .'

When he's in the hall, of course, it's at the back. Some chorus masters might resent this - all that effort and energy only to see a conductor, Kertesz, say, or Karajan, or Boult or Giulini or Barenboim, deliver the thunder on the opening night. Not Oldham. 'I've always known that's been my job, to tune the instrument exactly the way the conductor wants.'

Instead, he takes enormous pleasure in watching the visitor mould his voices into different shapes and textures. Giulini most of all: 'He said to me once, 'You've a marvellous chorus, but the voices are all white. Now you have to look for the reds and the blues and the greens.' I've thought about that a lot.'

He also prides himself on the professionalism of his entirely amateur team. One year, he couldn't get hold of Karajan to find out whether he wanted the Chorus to learn the Italian Latin or the German Latin version of the Bach Magnificat. 'When he at last arrived, my first question was, 'Which do you want?' And he said, 'Which have you prepared?' And I said 'Both.' '

Other years, he's sat back and watched his singers steal the show. 'I insist on discipline and I tell the chorus, don't imitate the orchestras. They're very often bored - the LSO in the old days was terrible. Many festivals ago, Colin Davis had come up to conduct Beethoven 9. It was a last minute thing and he was on very bad terms with the orchestra he had to work with. They turned up late for rehearsals, they played like clowns, I could see he was getting white with anxiety.

'There's nothing for the chorus in Beethoven 9 until the last movement, and from the moment they came in - they had worked a year for this concert and nothing was going to stop them - they sang with such tremendous verve that the orchestra started to play well too and the concert was a huge success.'

Oldham leans back in his chair and picks some tobacco from his tongue. 'Now that's what I like,' he says roundly. Which brings us, of course, to the time he bypassed the conductor altogether, only this time he's not mentioning any names. 'A French conductor,' he says coyly. On this occasion, he was so appalled by what he heard, he advised the chorus to 'sing it the way I taught you at rehearsals'. He's a bit embarrassed remembering this - 'the only time I've done it' - but the end, it seems, justified the means. 'The conductor afterwards said, 'that was marvellous'. So we got away with it.' Oldham grins. 'I'm ruse, you see.'

(Photograph omitted)