I've always thought of Tasmin Little as a young fiddle prodigy, partly because that's how she first shot to fame, and partly because that's the way the photos still present her - with an impish little-girl grin, as the picture heading her much-visited website confirms. But she's 40, and moving into that middle age where many musicians change tack. Her change - like Anne-Sophie Mütter's - is from playing to conducting as well, and her first forays into Beethoven have been greeted with acclaim.

"Turning my back on the audience and waving my arms around is a new experience for me," she says. "And in Beethoven's violin concerto, there are many spots where an orchestra needs help, and a strong lead is essential. Obviously, you can't play and conduct at the same time, but you're not playing in the tutti, and setting up the first movement is critical. When things get going, then I can pick up my fiddle and join in. It's very satisfying to shape the performance from the start." Where will this end? "I have no plans to forsake playing altogether. I don't regard myself as a conductor."

The concert in which she will lead the Britten Sinfonia on Wednesday will also be demanding, but in a different way: she'll be sitting down as a member of an octet, standing up to play a Bach concerto and then melding with a viola soloist for Mozart's magnificent Sinfonia Concertante.

She owns a 1757 Guadagnini violin and has the use of a Strad: which will she use at the Queen Elizabeth Hall? "I haven't decided," she says. "My Guadagnini is good for creating a huge array of colours; the Strad provides authority and power. I suspect I will choose the Strad. But when we perform in Cambridge, where the hall has a nice acoustic, and projection is less critical - and the colour aspect becomes more possible - I may use my Guadagnini." Which is more valuable? "The Strad." How much? "Oh, we can't print that."

Wednesday (0870 401 8181; www.rfh.org.uk)