Mary, Queen of Scots, Hackney Empire, London

Elizabeth I vs Mary, Queen of Scots. This was one bout that history decreed would never happen. The two queens never met. But when the playwright Friedrich Schiller turned the stand-off into a face-off, it was only a matter of time before opera made a song and dance of it.

Elizabeth I vs Mary, Queen of Scots. This was one bout that history decreed would never happen. The two queens never met. But when the playwright Friedrich Schiller turned the stand-off into a face-off, it was only a matter of time before opera made a song and dance of it.

Donizetti's Maria Stuarda (Anglicised as Mary, Queen of Scots) is famous above all for that one scene, a scene triumphantly blurring the boundaries between on- and off-stage rivalry as two divas come head-to-head for the big prize - the audience's approval. The illicit thrill of watching two star singers raise their game to send each of us out to the interval singing their praises is quite an incentive.

Mary, of course, is the title role and she gets to fling the final insult - "Royal bastard!". It doesn't have quite the same ring in English as it does in Italian, but it does the job. Elizabeth has been trounced, and the only card she has left to play is the one sanctioning the removal of Mary's head. It's not quite the winning hand she had hoped for.

Some pretty starry divas have lined up for this confrontation in the past; it's surely the main reason for doing the piece. A vehicle for two fabulous singers, an exhibition of vocal style and temperament more than it is a viable stage drama. So, with all due respect to two decent singers - Anne Mason (Mary) and Jennifer Rhys-Davies (Elizabeth) - one has to wonder why English Touring Opera chose to do it at all. It doesn't lend itself to cut-down staging. Period opulence is almost as essential to its success as vocal prowess; and ETO's budget stretches to neither.

Even so, you would at the very least expect a level of professionalism in the look of the show, but Soutra Gilmour's designs, poorly lit by Aideen Malone, fell well short of the mark. The steel-framed set with its furtive sliding panels, some with translucent tapestries inlaid, was a simple way around the scenic demands. The costumes were not.

Poor Anne Mason's Mary was marked out as a victim from her very first entrance, an Elizabethan fashion victim in what lambs to the slaughter might be wearing this season, complete with fake-fleece trimmings. Most of the costumes looked like they were at the first-fitting stage. Jennifer Rhys-Davies could have hidden most of the cast under her bustle in Act III.

Their singing, though, kept my attention from straying to the uneven hemlines. Rhys-Davies deployed the pyrotechnics with some aplomb, dispatching her fury rashly (and quite excitingly) above the stave. If she could just find more beauty in the sound, more fullness at the top. Anne Mason had quite the reverse problem, sounding hectic and stressed in the coloratura but blossoming in repose. She had a really decent stab at the huge final scene where Janet Baker is forever in my inner ear. This is the best music in the piece, Mary's voice floating free of the chorus, primed for eternity.

One other voice made an impression - the tenor Nicholas Ransley as Leicester. But as yet it's a good voice squarely used. He needs to open up the phrasing and free himself. According to the press information he wears the same boots here as Johnny Depp wore in Pirates of the Caribbean. So far, precious little of Depp's swagger has rubbed off.

Noel Davies conducted a tight, brassy little band well complementing the small but spirited chorus. Not much evidence of a director, though. James Conway is credited, but to say that the evening runs the gamut of emotion from A to B would be pushing it a bit.

Arts Theatre, Cambridge (01223 503333) tomorrow; then touring ( www.englishtouringopera.org.uk)