Observations: The right choir for a Carroll

Not many choral directors can claim to field daily calls from Hollywood composers Hans Zimmer, Danny Elfman and Craig Armstrong. Jenny O'Grady is one such director and her phone has barely stopped flashing up LA numbers since she created Metro Voices 15 years ago. Her latest project is providing vocals to this year's eagerly anticipated Alice in Wonderland.

"The soundtrack follows in the tradition of Elfman's other films. Like Sleepy Hollow it has that wonderful ethereal quality to it but it's also quite meaty when it needs to be," explains O'Grady. Metro Voices have featured on all of Tim Burton's last decade of films: Sleepy Hollow, Big Fish, Charlie and the Chocolate Factory, Corpse Bride and Sweeney Todd. Such frequent collaborations have yielded a good friendship and Burton enjoys playing the occasional practical joke on O'Grady. He forced her into being an extra in Sweeney Todd and then insisted she appeared on camera.

O'Grady was urged to set up a professional vocal group by key music industry figures. With a 20-year career as a professional singer behind her, she accepted the challenge and once Metro Voices had recorded the unforgettable soundtrack for Baz Luhrmann's Romeo + Juliet, the rest was history.

A core of 25 professional singers work with O'Grady on most projects, but she has countless singers from every genre, from opera to gospel, on her books. The group has recorded over 100 film soundtracks, including City of Angels and Moulin Rouge.

Why do Hollywood composers look across the Atlantic for vocalists? The answer is surprisingly simple. "Sight singing," explains O'Grady. "In LA choirs have to spend time learning music before they can record, but in the UK we can turn up on the day, sight sing and record almost straight away." Refusing to name a favourite soundtrack, O'Grady describes working on Mamma Mia! as a "dream come true" – it did require a little less sight singing than usual, after all.