of the recent series of Ba/lo in maschera performances at Covent Garden, he said that the great pleasure of a run of opera performances was the chance it gave him to grow into the work and develop his interpretation . 'I am not the man who can do everything well at once. I'm not that kind of animal. I need to go through a work over and over again . It's the same with books . The ones I love I can read again and again , and graduall y derive more from them.'

When he comes to a work for the first time - as with this month's A Midsummer Night's Dream at Glyndebourne - he first pores over the score and makes it part of him. Only then does he consider hearing records of other conductors. 'If you begin by listening to others, I don't believe that you ever reach the crux of the piece.'

What has struck him particularly about The Dream ('it was about time Glyndebourne and Britten were reconciled ') is the intense theatricality of the whole. 'I suppose you might find the score by itself a little thin if you divorced it from the libretto , but the setting is so masterly that in the opera house, it must be wholly convincing. I also think that Pears's adaptation of the play is masterly. What a collaboration that was! '

His other opera this season at Glyndebourne is Fidelio. 'As with the Ba/lo, I felt that the interpretation improved out of recognition as the performances progressed . Particularly in a small house, it is very difficult to bring off - everythjng is so obvious. I think that it was only in the television performance the winter before last that everything fell into place. Without Leonore 3, the work is less camouflaged, much more naked .'

Bernard Haitink rehearsing th e new production of 'Fidelio' at Glyndebourne in 1979, with Peter Hall