'It isn't accurate at all. The contemporary music was there, in quantity, and I was always at pains to get good people to do it. But I was educated in the classics, and when I came to the BBC I was just as much concerned to promote Haydn and Bach as Gerhard or Nono. When I look back at my Proms programmes, the number of new-old works was greater than the number of new-new works, and that to me was always just as important.' One can understand the need to push for Monteverdi or Schutz or anything now embraced by the Early Music label, but Haydn and Bach? 'Before I started on the Proms, there was one Haydn symphony played in five seasons - No 88 it was. So I tried to include about six a season, but I didn't always succeed, because it was common knowledge that Haydn drove audiences away. You had to back him up with some crowd-puller. As for Bach - I well remember a friend of mine being told to get out of a taxi when the driver found that he was on his way to Broadcasting House to conduct two Bach cantatas. There were a lot of people who felt like that.' Including some of the modernists? 'Some. When Luigi Nono first came over, he said: 'William, what on earth is all this Bach for?' But after, composers began to find it fascinating - not just Bach, but the earlier discoveries. Think of Maxwell Davies. This was a period of expansion in all directions.'
It is startling now to look back to the pre-Glock days and see how stultifyingly narrow Proms programmes could be. 'When I arrived at the BBC I found that the Proms were planned by committee. The idea seemed to be that you looked at the previous year's programmes and just made a few changes - no question of starting with a blank sheet. I knew this would have to stop.' Nowadays one often hears the opposite complaint - that the one-man system is tyrannical, and that committee planning is more democratic. 'I don't think any serious activities can be managed by committees. They simply can't achieve great things. You need one person's vision. I could have made what was then a radical new idea, such as including a Bach Passion, and someone would have vetoed it.'
Have there been any striking changes in the character of the Proms under either of Glock's successors, Robert Ponsonby or John Drummond? 'There have been adaptations - to new expectations, new instrumentations. But not much. Perhaps there's less music of the classical period than before.' What about the nature of contemporary music? The days of Pierre Boulez and the Round House new music Proms - of what one recent Radio 3 Head of Music Programmes called 'hair-shirt stuff' - seem long gone. 'I don't know. I read this expression 'post-modern'. It usually means going back or trying very little. I don't know whether Pierre still thinks that his own music is likely to lead to the next remarkable period - maybe not. A lot of young people dismiss him now.' The growing view is that Boulez is - as conductor and composer - intolerant, narrow, overly scientific. 'I do feel that there has been a third period with Boulez which is very little understood. It starts with Rituel, and everything since then - well, you can't possibly describe it as cold or non-melodic. And the new version of Visage Nuptial - that's a beautiful piece.'
Old friends, such as Boulez or Elliott Carter, seem to look on the current state of new music with deep despondency. Does Glock share their point of view? 'I do rather. There's so much I hear now which is baffling because it's so simple. There are good things, though. I've been struck recently by some pieces by Judith Weir. I listen to Radio 3 quite a lot late at night and sometimes I hear encouraging things on the new music programmes. And Birtwistle gets better. He's gained enormously since breaking away from things like concert-making and going and living in France, where he can just concentrate on his work.' Another friend of Glock, Igor Stravinsky, once said that nothing was less certain in any age than genius. 'Yes, I sometimes think there was a great flame that lasted from the beginning of the century until about 1970 - about the time of Stravinsky's death - and that now we're a bit lost. But I remain optimistic. Something will grow, though maybe not out of what's being done now.'
Mention of Radio 3 a moment ago inevitably prompts me to ask what Glock thinks of the new regime, but he refuses to be drawn. 'I'd have to listen to more to comment.' But does he still feel just a little proprietorial? 'Twenty years ago I would have done, but I'm getting a bit elderly now.' And with a genial smile, Sir William indicates that he has said all he's going to say on that subject. Now, at 84, he has other things to occupy him - his Schubert series at the South Bank, for example. 'It hasn't all turned out the way I originally wanted. When you have lots of artists there are endless changes and some spoiling. But in some cases the changes were interesting. At first I wanted Robert Holl to include some of my favourite neglected songs in his Schwanengesang recital, but he preferred to have his pianist play some late solo pieces - and that's worked out rather well. The first concert is a smashing affair - the two greatest chamber works, the String Quintet and the G major Quartet. The Quartet's a fantastic work. That last movement - it goes reeling along. It must be hellish to play.'
And after Schubert? 'More South Bank series - Handel, and then Stravinsky - one a year, so I'll probably be gone by the time they want me to do anything about Stravinsky. If not, that will be in collaboration with Boulez.' It won't be the familiar Stravinsky. 'I want to include as many of the late, serial works as possible - the works that are still resisted. Julian Bream once described late Stravinsky to me as 'dry biscuits'. I admit they don't invite enthusiasm of the usual kind.' Nicely put. I remember what a friend of mine said about Carter: 'I like everything about it except the sound it makes.' 'Oh, but the sounds are so much his own. Stravinsky always had that wonderful ear. It's there in Movements as much as in Firebird. You have to work to meet it, to concentrate - but is that such a terrible thing?'
South Bank Schubert series, 4 Feb-2 March. Booking: 071-928 8800