Colin Matthews' Three Enigmas (1985) for Cello and Piano.
Published by Faber Music.

'To explain the title would, obviously, take away the enigma: but there is nothing particularly mysterious intended, only an indication of the rather introverted, hermetic nature of the music (and the musical processes employed). The work is, however, simple to describe – the outer movements are both basically fast and hectic, though with moments of repose, and a feature of both is that cello and piano have extended passages in unison. The central piece is perhaps the most clearly ‘enigmatic’: a virtually solo mediation for the cello with only the most simple of piano accompaniments.'

~ Colin Matthews