Birtwistle has always been fascinated by drama and the theatre, which began to manifest itself in compositions for the concert platform even before he wrote anything for the lyric stage. Myth and ritual have been continuing preoccupations too. When Gawain, the fifth of his music-theatre pieces, was first performed at Covent Garden in 1991, it was the first to be described as an ‘opera’, as if in recognition of the houses for which it was designed and of the expectations of people who go there to listen to stories told through singing. The linear nature of Gawain does indeed fulfil the traditional story-telling function of opera, dramatising and illustrating a sequence of events as narrated and elaborated by David Harsent in a libretto based on the Middle English epic of Sir Gawain and the Green Knight.

At King Arthur’s court at Camelot, it is Christmas. Invisible to the court are Morgan Le Fay, the King’s half-sister and aunt of Gawain, plotting to destroy the court and to keep Gawain in her thrall, while the course of events is commented upon by her partner in seduction, the Lady de Hautdesert. Arthur demands diversion; they reassure him he is not going to be disappointed. After a masterly build-up of tension characteristic of the composer, the Green Knight enters on horseback and issues a challenge: he is willing to receive a blow from any of the grail knights on condition that a year and a day from now whoever has agreed to the wager will accept the same from him. Gawain responds, decapitating the Green Knight with one blow, who then picks up his head and rides off, while continuing to sing through it with a reminder of the bargain he has struck. I’ve long cherished this theatrical moment, along with the appearance of the ghost of Hamlet’s father and the statue of the Commendatore. My acknowledgments by the way, in the Birtwistle, to Andrew Clements’s synopsis in the NMC booklet as well as his excellent note.

This recording derives from a BBC broadcast in April 1994. It is, of course, a welcome addition to NMC’s representation of Birtwistle’s stage pieces. But take note: it comes from a revision of the original 1991 production in which substantial cuts to the score were made, principally in the cyclical masque-like Turning of the Seasons section which closes Act 1. At the balancing point of the opera at the beginning of Act 2, when Gawain embarks on his journey to the Green Chapel, after a year and a day have elapsed, to confront his fate, more music is lost from the only extended section for orchestra alone. The losses amount to about 30 minutes in all and are particularly damaging to the masque of the turning seasons – the climax of Act 1 and a magnificent inspiration. Yet Gawain is already a long evening. In an exceptional recent performance at the Barbican by the BBC Symphony Orchestra conducted by Martyn Brabbins they were restored; you will have been able to make up your mind about them if you caught the broadcast on July 15.

On NMC, John Tomlinson as the Green Knight has peerless authority and you can hear his every word. He was undiminished in quality at the Barbican performance I attended, though by then the rest of the cast had changed. François Le Roux here, after a slow start, fleshes out the character of Gawain in Act 2 and becomes a worthy adversary, returning to Camelot at the close after another journey, this time of self-discovery. Marie Angel and Anne Howells as the two schemers, usually hunting as a pair, make only a generalised effect and you will need the libretto to help you register what they’re singing about. Ideally, of course, we need a DVD – perhaps one from last year’s Salzburg production? – to get words, music and stage picture together and the experience of Gawain at full force. The effect overall of this performance, in audio alone, is claggy and, I suggest, too little differentiated.