In October 2021, the Cosman Keller Art & Music Trust began supporting the Castalian String Quartet in a new residency at the University of Oxford, established in memory of Hans Keller.

Founded a decade earlier, the Castalian String Quartet had taken the international chamber music scene by storm. Having won first prize at the Lyon International Chamber Competition in 2015, they were selected as YCAT artists the following year. In 2018 they won the inaugural Merito String Quartet Award and Valentin Erban Prize, as well as being awarded a prestigious Borlotti-Buitoni Fellowship. In 2019 the Royal Philharmonic Society named them Young Artist of the Year. Their concert-giving took them to the world’s most prestigious concert venues, including the Berlin Philharmonie, the Vienna Konzerthaus, the Elbphilharmonie in Hamburg, the Paris Philharmonie, the Amsterdam Concertgebouw, New York’s Carnegie Hall and Lincoln Center, and of course the Wigmore Hall in London.

The Trust was delighted to be able to support this exciting new partnership between the University of Oxford and one of the best young string quartets in the world. The Hans Keller Residency allowed the Castalians to integrate a diverse range of educational projects within an annual concert series that combined the masterpieces of the string quartet repertoire with new and unknown music, including works written specially for the Castalians by Charlotte Bray, Mark Simpson and Sir Mark-Anthony Turnage.

The Castalians’ educational work included coaching student ensembles, side-by-side performance with students, and workshops and performances of the works of student composers. Through pre-concert talks, lecture illustration and public seminars they have also supported the research of Oxford academics, including Professor Laura Tunbridge’s work on the history of the string quartet. Their work with St Anne’s Camerata has brought inspiration to string players both at university and school level, while their imaginative outreach work attracted additional funding from another donor to take them into Oxfordshire primary schools.

The Castalians also took part in several public Faculty of Music events on the work of Hans Keller, including performances and discussion of his functional analysis scores, some of which the Quartet has also recorded. (See here for Nicky Swett’s ongoing Words on Wordlessness podcast, which features these performances.)

For four years, the Castalian String Quartet has been a vital presence in Oxford, bringing the very highest standards of chamber music-making to the University, schools, and the wider public. This very special partnership came to an end in September 2025 when the Quartet announced its dissolution. The outstanding artistry and generosity of this remarkable ensemble will be greatly missed.

However, all four members of the Quartet continued to contribute to the chamber music provision of the University in 2025-26, supported by the Trust, which has funded a ongoing programme of concerts and educational activities, also featuring the Adler Quartet (founded by two former members of the Castalian Quartet), the Villiers Quartet and others. The 2025-26 academic year is an important milestone for music at Oxford, with the opening of the University’s new Schwarzman Centre for the Humanities, where we trust that world-class chamber music will continue to flourish and be brought to a wider audience than ever.

The continuing vitality of the string quartet was of enormous importance to Hans Keller.  He considered it to be the most purely musical form of composition, and his contribution to its development in the second half of the twentieth century was immense. Keller coached many of the leading British ensembles of his time, and during his 20 years at the BBC he not only developed performance opportunities and enabled the best quartet-playing to be heard, but also did much to broaden awareness of this remarkable repertoire. Through his own broadcast talks and lectures around the country, Hans Keller made an outstanding contribution to the education of the audience for chamber music, and he had a unique ability to speak meaningfully both to musicians and their public at the same time. He inspired many composers to write new works for string quartet, including Benjamin Britten, who dedicated his own Third String Quartet to the man who, he said, ‘knows more about the string quartet, and understands it better, than anybody alive’.