Royal Philharmonic Society prizewinners and resident ensemble at Oxford University, the Castalian Quartet is in-demand on the world stage.

The Castalian String Quartet is taking the international chamber music scene by storm. Gaining renown for interpretations “full of poetry, joy and sorrow, realised to such perfection” (The Observer), they have recently been announced as the first Hans Keller String Quartet in Residence at the University of Oxford.

Formed in 2011, the quartet studied with Oliver Wille at the Hochschule für Musik, Hannover, before being selected by the Young Classical Artists Trust (YCAT) in 2016. They were awarded First Prize at the 2015 Lyon International Chamber Music Competition and in 2018 were recipients of the inaugural Merito String Quartet Award and Valentin Erben Prize, and a prestigious Borletti-Buitoni Trust Fellowship. The ensemble was named Young Artist of the Year at the 2019 Royal Philharmonic Society Awards.

Recent debuts include New York’s Carnegie Hall, the Berlin Philharmonie, Vienna Konzerthaus, Hamburg’s Elbphilharmonie, Paris Philharmonie and the Concertgebouw in Amsterdam. The Castalian String Quartet performs frequently at the Wigmore Hall in its home city of London. In 2018 they recorded Haydn’s Op.76 quartets for the Wigmore Live label and were joined by pianists Stephen Hough and Cédric Tiberghien, violist Isabel Charisius and clarinetist Michaels Collins for a Brahms and Schumann series in the 2019-20 season. Their next Wigmore Hall cycle will feature all three quartets by Benjamin Britten. The quartet often appears at festivals such as Spoleto USA, Aldeburgh, North Norfolk, Cheltenham, East Neuk, Lockenhaus and Heidelberger Frühling. Recent and upcoming premieres include works by Charlotte Bray, Edmund Finnis, Mark Simpson, Simon Rowland-Jones and Sir Mark-Anthony Turnage.

The Castalian String Quartet’s 2022 release Between Two Words (Delphian Records), presenting music by Orlando di Lasso, Thomas Adès, Ludwig van Beethoven and John Dowland, was given a double five-star review as BBC Music Magazine’s ‘Album of the Month’: “this outstanding disc offers listeners a true philosophical journey…a series of intricately connected works, each performed with rare beauty and originality by a quartet at the height of its powers…[the Heiliger Dankgesang from Beethoven Op.132] is nothing short of a revelation in its lucidity of line and sheer beauty of sound.”

The quartet’s name is derived from the Castalian Spring in the ancient city of Delphi. According to Greek mythology, the nymph Castalia transformed herself into a fountain to evade Apollo’s pursuit, thus creating a source of poetic inspiration for all who drink from her waters. Committed to inspiring a diverse audience for classical music, the Castalians have performed everywhere from the great concert halls to maximum security prisons and even the Colombian rainforest. When not on stage, Finnish first violinist Sini Simonen bags Munros, Irish violist Ruth Gibson teaches yoga and the Welshmen, second violinist Daniel Roberts and cellist Steffan Morris, get overly emotional about rugby.

Sini Simonen - Violin

Finnish violinist Sini Simonen enjoys an active international career as a chamber musician and soloist. She is the leader of the Castalian String Quartet. Recent and forthcoming performances include recitals at the Carnegie Hall, Washington Library of Congress, Berlin Philharmonie, Hamburg Elbphilharmonie and Amsterdam Concertgebouw. The quartet hold the position of Hans Keller String Quartet in Residence at Oxford University. This season they embark on a Bartòk series at the Wigmore Hall.

Sini studied at the Sibelius Academy, Musikhochschule Hannover and Musik-Akademie Basel with Lara Lev and Rainer Schmidt among others. Masterclasses and collaborations with Ferenc Rados, Gerhard Schulz and Sir Andras Schiff provided important influences.

From 2013 to 2017, she was a violinist of Esbjerg Ensemble, one of Denmark’s oldest chamber groups. The ensemble is comprised of a string quartet, wind quintet and percussion, and it is known for its innovative programmes combining contemporary and classical works.

Collaborations with composers are a vital part of her musical life. Recent and upcoming commissions and premieres of chamber music include working with Charlotte Bray, Mark-Anthony Turnage, Thomas Larcher, Edmund Finnis and Francesco Antonioni.

Simonen has won top prizes in several major international violin competitions including the Flesch, Lipizer and Cremona competitions. She has also won prizes in the Brahms, Lyon, ARD and Banff chamber music competitions. Her recordings include Bach’s double violin concerto with Helsinki Strings (Warner), Vivaldi’s concerto for 3 violins (tacet) and an award winning album featuring quartets by Beethoven, Adès and her own arrangements of renaissance music (Delphian).


Daniel Roberts - Violin

Daniel Llewellyn Roberts (b.1987) studied with Nigel Murray and Jan Repko. He is a graduate of the Royal Northern College of Music, Manchester, holds Masters degrees from the Royal College of Music, London (as a Yehudi Menuhin Scholar), and the Hochschule für Musik, Theater und Medien, Hannover, and has twice been a Leverhulme Chamber Music Fellow at the Royal Academy of Music, London.

As a soloist, Daniel has appeared in Hong Kong City Hall, the Queen’s Hall, Edinburgh, the Hindemith Cabinet, Frankfurt, and the Sudler Recital Hall, Yale University. He was the recipient of the 2009 Musicians Benevolent Fund ‘Emily English’ Award for ‘most outstanding violinist’, and the 2010 Philharmonia Orchestra MMSF ‘John E. Mortimer’ prize.

Alongside his role as violinist with the Castalian String Quartet, he performs internationally as a chamber musician and has collaborated with musicians such as Simon Rowland-Jones, Tom Poster, Levon Chilingirian and the Primrose Piano Quartet.

Daniel is in demand as both a violin and chamber music teacher, previously holding positions at Birmingham Conservatoire and St. Paul’s Girls’ School, London, and giving masterclasses at St. Mary’s Music School, Edinburgh, and in various music schools and conservatoires in China. He teaches on the Xenia Chamber Music Course in Italy.

Daniel is a Yeoman of the Worshipful Company of Musicians and is extremely grateful to them for the loan of a fine violin by Joseph Guarneri filius Andrea of 1705.

Ruth Gibson - Viola

As an internationally recognised chamber musician and soloist, Irish born Ruth Gibson has appeared at the world’s leading concert halls, including Wigmore Hall, Lincoln Centre, Het Concertgebouw, Queen Elizabeth Hall and Berlin Konzerthaus.

As soloist she has performed under Sir John Elliott Gardiner with the Bournemouth Symphony and has broadcasted for BBC4. Recent performances include Woolrich’s Ulysses Awakes for Solo Viola and Strings at Nurnberg International Chamber Music Festival and Mozart’s Sinfonia Concertante with Dmitry Sitkovetsky at Barry Douglas’ Clandeboye Festival in Belfast. In 2015 she became a Park Lane Group Solo Artist and preformed the viola works of Pendercki at the Purcell Room in London.

Alongside the quartet, she plays regularly with the Manchester Collective, Nash Ensemble and  Scottish Ensemble, having recently performed at Wigmore Hall, Cadogan Hall, Berliner Philharmoner and toured the US with Joshua Bell. She has toured China, South America, Russia, Finland and Mexico as Principal Viola with Camerata Ireland, and regularly guests as Principal Viola with Manchester Camerata, Aurora Orchestra and City of London Sinfonia.

Ruth is a laureate of numerous prizes. As a member of the Finzi Quartet she was a Prize Winner of the 2010 Royal Over Seas League Competition and the 5th Trondheim International String Quartet Competition in Norway. Other notable awards include the Tillett Trust, the Tunnell Trust, the Kirckman Concerts Society, the Swiss Global Artistic Foundation, the Hattori Foundation Awards and the Park Lane Group Award.

Ruth is a tutor in Viola at the Royal Northern College of Music in Manchester and was the founder and artistic director of the String Quartet Collective at the Royal College of Music in London from 2012–2016.

Steffan Morris - Cello

Welsh cellist Steffan Morris enjoys a richly varied career as a soloist, chamber and orchestral musician. He studied at the Yehudi Menuhin School with Thomas Carroll and then with Heinrich Schiff at the University of Music and Performing Arts in Vienna. For the last 4 years, Steffan has been Principal Cello with the Royal Northern Sinfonia and has been a guest principal with Orchestras such as the Amsterdam Sinfonietta, BBC Symphony Orchestra, London Philharmonic, Royal Liverpool Philharmonic and Royal Philharmonic Orchestras. Much in demand as a chamber musician, he has performed internationally alongside musicians like Alasdair Beatson, Alexander Lonquich, Timothy Ridout, Maria Wloszczowka, John Meyerscough and Antje Weithaas. Prizes include first prize at the Banff and Bordeaux String Quartet Competitions. He has played as a soloist with orchestras such as the Royal Northern Sinfonia, Sinfonia Cymru and Cardiff Philharmonic Orchestra. He has taught at the Yehudi Menuhin School, Royal Welsh College of Music and Drama and the Royal College of Music.

He plays on a cello made by Johannes Teodorus Cuypers made in 1770, generously on loan from Private Sponsors.