Not that Duffy's defence of her - or anything else in the work, for that matter - is skilfully dramatised. With the locking-out taking place just before the interval, both halves of the piece shows us John Finn's Purcell playing host to ghosts, warning figures and scenes from his past. The first time, these are products of an exhausted, late-night doze at the keyboard; the second time, the effusions of his feverish, sick-bed slumbering. Accompanied by a quartet of musicians up in the dinky gallery (one of whom performs on a scrupulously authentic electric keyboard), extracts from The Fairy Queen, The Libertine, Don Quixote et al are duly worked into the proceedings. (Thus, to a rendering of "Hither this way", Purcell finds himself, like the hero of his King Arthur, the subject of a vigorous tug-of-war between competing interests.) The maladroitness of some of these interpolations would be easier to bear if the singing just occasionally took off from the pot-holed runway of bare adequacy.
Whatever you may think of their dramatic finish, David Pownall's various plays about composers always address meaty issues - the sacrifice of individuality to the needs of the state in Master Class, his Shostakovich/ Prokofiev piece; the question of what, if anything, is the duty of a composer in war (one of the topics raised by Elgar's Rondo, which examines the protagonist's spiritual and creative crisis after the demoralising reception of the Second Symphony).
The trouble with The Masque of Henry Purcell is not a shortage of such themes, but the fact that they are thrown up haphazardly and very rarely treated to a spot of development. The one that comes through strongest is the idea that music is a healing freedom to the listener, but destroys the enslaved composer at the mercy of fickle patrons, is the one that comes through strongest. Plangently ironic, then, that his friends should have demonised Frances, who was even criticised over the "dedication" to the works of his she published after his death. But the focus of The Masque is, at times, enfeeblingly uncertain. The clunking interventions of, say, Geoffrey Harris's camp Charles II ("When is a monarch more innocently employed than at the races?") or Brenda Longman's Queen Mary ("War was so costly we had to set up a new bank to finance it") give the composer an unnecessary refresher course on his recent past and the audience a patchy crash course in his Life and Times. They don't contribute to a decent theatre piece about him.
n 'The Masque of Henry Purcell' is at Southwark Playhouse, London SE1 (0171-620 3494) to 28 Oct