[2] He attended Bedales School,[3] and was awarded a scholarship to the Royal College of Music, where he studied clarinet with Frederick Thurston and piano with Arthur Alexander.
[5] Their recordings of chamber music for both woodwinds and strings were reissued in 2011, including the works for larger ensembles which were the reason to found the ensemble, such as Beethoven's Septet and Octet, Schubert's Octet and Ravel's Introduction and Allegro, played with Osian Ellis (harp), Richard Adeney (flute), Emanuel Hurwitz and Ivor McMahon (violin), Cecil Aronowitz (viola) and Terence Weil (cello).
[7] He was a founding member of The Chamber Music Society of Lincoln Center in New York in 1969 and played with them for 20 years.
[7] De Peyer played first performances of concertos by Arnold Cooke, Sebastian Forbes, Alun Hoddinott, Joseph Horovitz, Thea Musgrave, Elizabeth Maconchy, William Mathias and Edwin Roxburgh.
[7] He premiered the Fantasy on an American Hymn Tune Op.70 for clarinet, cello and piano by Kenneth Leighton, commissioned by de Peyer, William Pleeth and Raphael Wallfisch and played by them at the Cheltenham Music Festival in 1975,[9] and Miklós Rózsa's Sonata for Clarinet Solo op.