Wapshott is multi-tasker who knows all the scores

Wapshott can sing a decent approximation of any vocal part and sight-read full orchestral scores at the piano. She can coach singers, direct chorus rehearsals, shadow movement directors, fine-tune diction in several languages. She can provide a shoulder for singers to cry on in rehearsals and nerves of steel in performances. And she can conduct. "An almighty multi-tasker," she calls herself. "A jack of all trades. A blagger who has to convince everyone, including myself."

But Wapshott does not look like she is blagging. She is a formidably capable and self-composed musician. And, because of the shoestring nature of Scottish Opera's touring productions, she is also unusually visible for a UK repetiteur: she not only works behind the scenes preparing the chorus and soloists for full productions, but also plays the role of orchestra and conductor in small-scale performances accompanied from the piano.

Her handling of Verdi's La traviata two years ago was stylish, shapely and rock-solid. She is currently travelling the country with a vocal score and a Yamaha upright, conducting, and playing, Verdi's Macbeth from Lerwick to Langholm.

"I love this tour," she says, looking undaunted by the prospect of a month of more performances. "I love changing people's opinions of what opera can sound like on the piano; proving it is possible to make a real range of colours. Audience members often tell me they were initially sceptical when they saw it would be a piano-accompanied performance, but that within two minutes of the overture they had forgotten there was no orchestra. For me, that is the greatest compliment."

She says Macbeth is the trickiest opera she has yet conducted from the piano because it involves so much ensemble work. Inevitably she can't provide the consistent direction a conductor would - she is busy using her hands for playing most of the time. In addition, tour performances are often staged in venues where sight-lines and luxuries such as off-stage monitors are limited, so the challenge of musical synchronicity at times comes down to, well, collective intuition.

"The trick is drilling the singers, getting them to take responsibility for their own rhythm," Wapshott says. "Some do struggle, especially more experienced ones who have got into the habit of always seeing the conductor and having monitors everywhere.

"I try to build up a good rapport between the cast during the rehearsal period and to work on subtle cues. I make sure my face is lit wherever we perform because there is so much I can do with my expression and movements." It is a bit like performing in a string quartet, she says. "Eventually the ensemble playing becomes second nature."

It is interesting that Wapshott compares piano-accompanied opera to chamber music; certainly the sense of intimacy and shared responsibility can bring similar benefits. "When singers are not just relying on someone else to give them cues but are actually listening to each other, you can hear that in their legato line. The danger," she says, "is nobody keeps the momentum going. Over the years I have learned how to make singers feel as though they are in control, but ultimately it is my responsibility to pace the thing ..."

For her part, the main challenge is not to strain her muscles through the sheer physicality of being an entire orchestra. She says she thinks "100 per cent orchestrally"; that she hears the score as it would be played in the original instrumentation.

"There is a risk of overplaying to bring out the breadth of sound I want. Often it is about knowing what to leave out as much as what to leave in. Mostly it is about staying relaxed." Paradoxically, she achieves more sound at the piano the more relaxed she is. Her shoulders gave her grief during The Barber Of Seville a couple of years ago; all those fast Rossinian repeated notes. She went to an osteopath, who pointed out her job is effectively that of an endurance athlete.

Luckily, Wapshott learned the right kind of solid, flexible technique back when she was a teenager. She grew up in Shropshire in a home that had plenty of sheet music lying around. Sight-reading always came easily: she did not practise much for lessons, but instead would play through any music that caught her fancy. "I am probably a good reader because I have such a short attention span..."

It is to do with more than that, of course; there is pattern recognition and anticipation. When faced with a full orchestral score there is no way to read every single note; the trick is speaking the composer's language fluently enough to guess. Plus there were the inescapable scales. "I practised scales for years and years and years," Wapshott says. "That's probably the real secret!"

After being an academic music undergraduate at Manchester University, postgraduate studies in accompaniment at the Royal Northern College Of Music and repetiteuring at the Royal Conservatoire Of Scotland, she applied for the Scottish Opera job and got it. "I fell into this because it is something I love," she says. "But it was also practical. Singers can pay an obscene amount of money to train, whereas there is often funding to study repetiteuring. We are sort-of working for the conservatoire - basically, they need us."

Wapshott recently took over as music director of the venerable Edinburgh Grand Opera music society and will conduct its production of Donizetti's L'elisir d'amore in the spring. She says she is interested in straight-up conducting and wants to do more, but is reluctant to say she wants to go down the route of being a conductor. "That would mean I would not play so much and I would hate that. Besides, some scores I would much rather play on the piano."

She mentions Claude Debussy's Pelleas et Melisande, which surprises me: wouldn't she want to conduct such a sumptuous panoply of orchestral colour? "Na," she replies. "It's just so wonderful to get those colours out of the piano."

Scottish Opera's Macbeth tours Scotland until November 1.