Ivor McMahon played second violin in the Melos Ensemble and participated with the group in the premiere of the War Requiem by Benjamin Britten, conducted by the composer.
[3] From 1950 until his death he was married to British violinist Nona Liddell, former leader of the London Sinfonietta; they had a daughter.
[4] McMahon recorded chamber music with the Melos Ensemble, its principal players Richard Adeney and William Bennett (flute), Gervase de Peyer (clarinet), Peter Graeme (oboe), Neill Sanders and James Buck (horn), William Waterhouse (bassoon), Emanuel Hurwitz, Kenneth Sillito and Iona Brown (violin), Cecil Aronowitz and Kenneth Essex (viola), Terence Weil and Keith Harvey (cello), Adrian Beers (double bass), Osian Ellis and Hilary Wilson (harp) and Lamar Crowson (piano).
In Françaix's Divertissement for bassoon and string quintet (1942), played with bassoonist William Waterhouse,[5] to whom the piece is dedicated.
[6] McMahon also recorded chamber music for smaller formations, such as the clarinet quintets of Mozart, Brahms, Weber, Reger and Bliss, with clarinettist Gervase de Peyer.