At the moment I’m doing the snagging on a four-minute piece for string orchestra, a new addition to Variations on Sellinger’s Round. The original piece was written in 1952 by six English composers, including Britten and Walton.  The set contains one miniature masterpiece: a ravishing lament by Michael Tippett. It’s for a Prom in August given by the English Chamber Orchestra. We have a rich collection of chamber orchestras in Britain, often overlooked and neglected by funders. Lower costs mean that they can programme more riskily than their bigger brothers can. And, again unlike the full-size bands, they can specialise. So in addition to the omnivorous ensembles (like the Britten Sinfonia, the Orchestra of St John's or the Northern Sinfonia) there are period bands (the Orchestra of the Age of Enlightenment, for instance) and contemporary groups (like the London Sinfonietta and the Birmingham Contemporary Music Group).

I’ve been touring with the BCMG this spring. When I started out as a composer, London was where the action was. Now, for me, the action has migrated north to Birmingham - whether it’s working with the BCMG, talking to composers at the Conservatoire, or writing for the City of Birmingham Symphony Orchestra. I’m looking forward to hearing the CBSO play my piece Falling Down next May. It’s a concertante written for the CBSO’s double bassoonist, Margaret Cookhorn. Andris Nelsons, the CBSO’s remarkable music director, will conduct.

The BCMG trip has reminded me that there are still some astute and adventurous arts administrators in the country, like Kevin Appleby at the Turner Sims in Southampton and Keith Nimmo at Wiltshire Music Centre. Dartington Summer School is lucky to have a marvellous administrator in Emily Hoare. This summer sees the end of my stint as artistic director of Dartington Summer School. I can’t list all the interesting things in the programme, there are too many, but one I’m particularly looking forward to hearing is an etude I wrote this year for Tamara Stefanovich. She has already given it an outing in Germany, but Dartington gets to hear it first in England.

Before Dartington I was associate artistic director of the Aldeburgh Festival and I’ve tried hard to forge links between the two organisations. One result is a songwriting project which started this spring at the Britten Pears School (where the poet Lavinia Greenlaw, the composer Huw Watkins, the singer Richard Edgar Wilson and I led the course) and moves to Dartington this summer with Dominic Muldowney and singers from Exaudi. Ray Davies is coming back to Dartington to teach songwriting, Harrison Birtwistle is around for a week and Philip Cashian is overseeing a project called 'Voices in the Garden' in which young composers will write for groups of singers to perform in Dartington’s beautiful gardens. And it won’t rain.

The summer school was founded - invented - by William Glock, who ran it, brilliantly, for its first 26 years. When Glock arrived at the BBC, as controller of music, he discovered that the Proms were planned by a 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 don't think any serious activities can be managed by committees’ Glock said. ‘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.’ And what did Glock want to offer listeners? ‘What they will like tomorrow’, he said. It was as essential to create new expectations as to satisfy the old.

Those new expectations included not just new music but 600 years of the back catalogue (‘new old music’ Glock called it). Glock was particularly keen to expand the representation of central figures, such as Bach and Haydn, who had previously been known only by a fraction of their work. 'Before I started on the Proms’, he said, ’there was one Haydn symphony played in five seasons…. So I tried to include about six a season’. This year there aren’t any.
William Glock was fortunate to work in a world before the advent of arts consultants and focus groups, and before the inexorable rise of the kind of arts administrator who seems to hate the arts. Glock was the real thing: a fine chamber musician and pianist, good enough to play at the Proms (he had studied in Berlin with Schnabel). He had the highest standards and was confident about exercising judgment and trusting his instincts and personal taste.

Glock had a greater influence on musical culture in post-war Britain than anybody. But how much has that influence lasted? Radio 3 has, shall we say, changed a great deal since his time. So have the Proms. But there is still a fragment of Glock’s vision, clinging on in a damp corner of Devon. Dartington Summer School (that unique, essential and irreplaceable part of our musical culture) is still there.

This year's Dartington International Summer School runs from July 27 to August 31.