reviewed by our music correspondent, Sir Tristan

Wagner is not the only composer to have been influenced by the Arthurian myth. The most recent work by Sir Harrison Birtwistle is a two act opera, Gawain, based on the poem Sir Gawain and the Green Knight. Its premiere was in 1991; since then it has been revived and is being performed at the Royal Opera House, Covent Garden, in a slightly revised and shorter form.

As most readers will know, the story tells of the arrival of a knight clad in green at the Christmas feast in Arthur's court. He challenges any of the company to strike him with an axe on the condition that in a year and a day the blow will be returned by the Green Knight. Gawain takes up the challenge, only to find that the Knight survives, and rides off, with the second half of the bargain still to be executed.

Twelve months later, Gawain, on his quest, seeks shelter at the castle of Sir Bertilak de Hautdesert. He is tempted by Bertilak's wife three times, and on the third occasion is led to dishonesty in his openness with Sir Bertilak.

On leaving the castle, Gawain goes to the appointed place and the Green Knight, on the third stroke, takes only a trickle of blood and does not slay him. The Green Knight is then shown to be Sir Bertilak transformed by Morgan's sorcery.

The libretto was written by David Harsent. Since the original poem required development into a suitable form for opera, he had to construct obvious theatrical `ports' and in order to instil Morgan's motives from the start, altered the running order of the piece.

The production included staggering special effects, of which the most impressive was a singing robotic head made all the more real by the occasional blink. Act One was centred on Arthur's Round Table, and the large doors through which the Green Knight entered were situated towards the back of the stage. The end of the act depicted Gawain's preparation for his quest and the passage of the year. In a clever arrangement, the set illustrated scenes from the Tres Riches Heures, commissioned by Jean, Duc de Berry (1340-1416) to depict the passing seasons.

The second act took place largely in the castle of Sir Bertilak. The attempted seduction of Gawain in the foreground was mimicked in the background by Sir Bertilak hunting.

Parallelism and dramatic irony gave much to the action. Arthur's plea to his knights "Who's brave?" is echoed by the Green Knight on his entrance. Gawain's arrival at Sir Bertilak's castle is an inversion of the arrival of the Green Knight at Arthur's court. Instead of a pagan knight entering a Christian gathering, Gawain is the pure knight arriving at the place where Morgan's godless spells hope to waylay him.

The music is unfailing in its edginess, and never leaves you feeling comfortable. Full of passion, it resembles Wagner in its intensity, but lacks conventional melody or harmony. Recurring themes, similar to leitmotifs, remind the listener of former action.

The music on its own would be quite a trial, but in conjunction with the full stage effects and, of course, marvellous plot creates a spectacular operatic experience.