Sir Charles Groves is celebrating his 75th birthday this month with a release of English string music on RPO records, with the RPO strings, 'who were wonderful', recording Elgar's Serenade for strings, Britten's Frank Bridge Variations, Vaughan Williams Tallis Fantasia and the Tippett Fantasia Concertante in just five sessions. How was this selection of music decided? 'There emerged a choice, what the RPO thought would be good, and then there were the usual pros and cons,' explains Groves. 'I've done a lot of British music - I like it - and it seems to me that if English conductors don't conduct it then one can't expect foreign conductors to either.' Sir Charles points to a list of nearly 100 contemporary composers, all British, all of whom are in his repertoire, the inventory including the expected Delius and Walton on to a contemporary range encompassing Thea Musgrave, Maxwell Davies, Alexander Goehr, Stephen Oliver and tens of others. 

Elgar, he reckons, is less English in a way. 'In compositional technique he really is more German. Sullivan and Sterndale Bennett and their generation all went to Leipzig to study, and though Elgar didn't - he was self-taught - the prevailing theory was that composers of the time had to go to Germany. For foreign audiences this is often the trouble with Elgar. I did In the South in Germany, and the reception of the orchestra was supercilious. There is a danger that conductors hang about - Elgar certainly didn't and not just because of the timing of 78 records. The timing of Elgar is extremely important in interpretation." 

Sir Charles turns to the Serenade for strings and points out one of the principal difficulties: 'The first and last movements are in compound time with a similar metronome marking, which makes it interpretatively rather hard. But the Serenade shows one of the greatest strengths of Elgar. His lighter music has all the melodic invention and scrupulous attention to detail that informs his great music. The slow movement is a miniature but a real microcosm of the slow movements of the symphonies and concertos. It is interesting that the Cello Concerto - so popular today - includes a slow movement hardly as long as the slow movement in the Serenade. As a great composer he was able to write short pieces that have the inspiration and grandeur of longer ones. 

'Each of the pieces on this disc has a slightly different string sound. The Elgar is beautifully mellow, while the Vaughan Williams has the contrast of the solo quartet and the echo of the orchestra in the acoustic of St Barnabas, Mitcham. Then the Britten is a virtuoso piece. Written for the Boyd Neel String Orchestra and first performed at Salzburg in 1937 it was a sensation - within two years it had been played more than 50 times. Britten understood string instruments - it is extremely rewarding to play, and string players love it. 

'The Tippett remains extraordinarily hard to play even though we know it now, but it is the Second Symphony that remains the most difficult. Tippett writes across the bar line which players find hard.' Sir Charles points to the main difficulty of this latest recording: 'Most of these works are normally given by chamber orchestras, so when you multiply the numbers - up to 50 strings - the problems of ensemble grow since many of the movements are extremely fast. On the other hand, the increased strength of sound is an advantage in the Tippett, especially in the climax of the fugue and the Pastorale.' Tippett was also featured in Sir Charles's 70th birthday concert at the Barbican, this time with the Ritual Dances from The Midsummer Marriage; the 75th birthday concert, also at the Barbican, will feature the Tallis Fantasia, Beethoven's C minor Piano Concerto (with Radu Lupu 'to whom I was a kind of midwife when he won the Leeds competition - I remember him as one of the great winners'), and Belshazzar's Feast, with the Brighton Festival Choir. 

Freelance life, now practised since leaving the ENO in 1979, allows Sir Charles 'to enjoy worrying about the musical side of performance'. He works regularly with all British orchestras and records with the RPO and English Sinfonia with whom he has made some acclaimed Mozart discs. He also conducts abroad a great deal. 'And people come and see me, partly due to age and experience. Young conductors discuss scores, and also how they can get a career going which is very hard. It is a beastly business not having an instrument, because good as it is to conduct a less than good orchestra it is frustrating, and they are not likely to get the opportunity to conduct a fine orchestra which would show them how their efforts are received. It is very rare people have it in them at a young age - Rattle has this rare gift of rapport. 

'Encouragement of young players is my main interest after my tremendous preoccupation with conducting. I am President of the National Youth Orchestra and take great pride from these young musicians. Together with their special enthusiasm I am astonished at capabilities of the young and that covers all types, wind band, brass band, as well as orchestral players. The standard is getting higher and higher-the small free lance chamber orchestras I conduct contain an amazing number of young players of the highest quality.'  

Out of the considerable shelf-space given over to Sir Charles's recordings, for which does he have special feelings? 'I can't say, really. I liked Dvořák's Sixth with the RPO - I always regret that the public only want to hear the New World and the G major. Then there was the Mass of Life in 1972, though it was in the shadow of Beecham, and also the early works of Elgar, Caractacus, for example. I have enjoyed recording so much British music but regret not having been able to record more other music. At my age you really have to get to grips with the feeling that you have never done everything you wanted to. Everyone feels the same - and the great thing is to face this with a sense of humour.' But conductors live for ever, I suggest. 'Some do, but you don't hear of the poor ones that go early. 

'Three conductors are my absolute idols, Beecham, Furtwängler - listen to his muscular slow movement of the Beethoven Ninth which is so easy to drop - and Toscanini who is rather unfashionable, but whose passion and dedication were second to none. The rhythmic figures in Verdi really meant something - listen to The Force of Destiny Overture, and La mer too, is wonderful. And I tried to perform light music as Beecham did - he had such a feeling for subtlety and a French delicacy of execution. One has got to have something to aim at. Look at Boult who constantly talked about Nikisch whom he revered. Today people talk about authentic performance as if nobody thought about it before. How to interpret is a constant preoccupation.' 

Sir Charles Groves died on June 20, 1992, aged 77.