It’s Dartington International Summer School’s 70th anniversary this August. I’ve been sifting through an enormous archive of letters, posters, programmes and photographs, lovingly housed in Devon by Jeremy Wilson, a retired surgeon who’s been connected with the Summer School for 60 years.‘Can we afford £10 for a typewriter?’ John Amis enquires of William Glock, the indomitable founder. ‘Conducting course a wonderful addition,’ Glock reports to the Gulbenkian, then chaired by William Christie; he goes on to grumble about the lack of an orchestra (there is one, now).

There’s a shopping list submitted by Stravinsky, for his legendary visit in 1957. It includes 14 lemons for one week; what on earth did he need all those for? Possibly gin and tonics. His students were Cornelius Cardew, Hugh Wood, Harrison Birtwistle, Alexander Goehr and Richard Rodney Bennett.

There are photographs of John Cage and Lou Harrison; a long report on the electronic studio run by Bruno Moderna; scribbled notes for lectures given by Glock, the Northrop Frye of new music. (It’s rumoured the only major composer not to have visited Dartington is Boulez.)

There's a 30-second film clip of Alfred Brendel horsing around in the 1960s, egged on by a giggling, teenage Imogen Cooper, sitting next to a (not entirely serious) folk dancing session, all in the gracious courtyard of Dartington: a dream of medieval buildings that could star in its own troubadour song.

Dartington Summer School has inevitably evolved. Some quests, though, remain constant: artistic excellence, money, the embracing of new ideas. The six artistic directors - including myself - have been practitioners, promoters and politicians, and damn resilient. (Those who run venues or institutions will recognise this list of virtues.) We’ve worked with tiny, dedicated arts teams, and operated within the large rural estate where the remarkable American heiress Dorothy Elmhirst established her vision of sustainability, the arts and social justice.

I curate an unusual four-week model: an educational school by day – this year there are over 80 courses ranging from medieval and baroque music to folk, poetry, jazz and multimedia, as well as opera and chamber music - and a festival of over 100 evening concerts. This makes the job unusually challenging. The international performers I invite are empathetic teachers, able to teach in a multifaceted and inclusive way, open to socialising and lively debates. Artists and students start after breakfast, and carouse until the early hours; they’ll collaborate in each other’s concerts. The teachers inspire instrumentalists, composers and singers on the cusp of a career, as well as passionate amateurs refreshing themselves on the deep landscape. Everyone believes music matters.

There’s no festival that doesn’t feel the shiver of the unknown. Funding is scarce, politics capricious; people’s incomes are squeezed. Dartington International Summer School has had its ups and downs, but it’s been sustained by fierce loyalty, and the support of the Dartington Trust and Foundation; and each year revitalised by a new generation of brilliant young musicians. Here’s to the next 70 years!

To explore this year's programme of events, visit: dartington.org