Andrew Stewart talks to Andrew Manze, a violinist putting the jazz back into baroque music
Prospective music students, or so it appears, used to be issued with a set of commandments designed to govern their progress into the profession and ensure they remained true to the classical repertoire. High on the list of imperatives stood a warning to anyone tempted to stray away from the fixed notes of a composer's written legacy: Thou shalt not improvise.

Although jazz has since become part of the curriculum at even the most conservative of conservatoires, and improvisation forms a key component of school music-making, prejudices against "playing by ear" have proved stubbornly ingrained among countless musicians who worship printed music as the gospel truth. Reports of the improvisational skills of Bach or Handel, research into unwritten performance conventions of the past and the evidence of practical textbooks on musical ornaments have added to the problems of early music performers, introducing thicker speculative fog to a business already shrouded in mystery.

It would be hard to criticise the safety-first approach adopted by many in the name of historical awareness, especially in the days when they and their audiences were adjusting to gut strings, valveless trumpets, colourful continuo groups and regular doses of poor tuning and cracked notes. But the younger generation of early musicians, technically accomplished and eager to experiment, have begun to grace performances of familiar works with genuine improvisations and spontaneous ornaments absent from composers' manuscripts.

Andrew Manze, who is among the most exciting of early music's young blades, has been described as the "Grappelli of the Baroque". Since his appointment in 1996 as co-artistic director of the Academy of Ancient Music, he might also qualify as the Stan Kenton of the 18th Century. The 33-year-old fiddle player, a Cambridge classics graduate and one-time devotee of the modern violin, makes no apologies for questioning received wisdom on the authentic performance of Baroque music, nor for introducing a fair percentage of his musical personality into such keystone works as the Bach Violin Concertos or Tartini's 'Devil's Sonata'. "Enough is known about Baroque playing for us to be able to say that most performers improvised then," he says. "But there are very few people today who are putting their money where their mouths are by trying to restore the tradition of improvisation. If we're going to look the public in the eye and claim to be historically aware as performers, then we've got to have a go at this. There are very accomplished early music performances that all too often lack that live and rather dangerous element."

Manze's undergraduate studies of textual criticism have supported his more recent attempts to make sense of Baroque music theorists, prompting him to question why rules were set down to curtail improvisation. Perhaps young performers were already indulging too liberally in the art for the comfort of older textbook authors? Matters of individual taste and style, he observes, were usually omitted from the theory books. Certainly, the deliberately mannered phrasing and jazz-like cadential flourishes in Manze's Harmonia Mundi recording of Vivaldi's concerto 'La tempesta di Mare', or his flamboyant readings of sonatas by Biber and Schmelzer reveal an individuality rooted more in instinct than any Baroque book of rules.

Such expressive freedom could prove a double-edged sword, especially if hatched in the recording studio. Surely improvisations that sound fresh and inspired on first hearing often become an unwelcome feature when played repeatedly on disc? "I am suspicious when musicians say they should be careful in recording because people might tire of hearing a particular trill or ornament," says Manze. "Improvisation is so much part of this music that if you don't do it you only present part of the story. Of course there's a dilemma in recordings, but the very act of playing ornaments in the studio helps keep the spirit of what you're doing alive. If you can get away from the temptation to be obsessed with every single note being absolutely 'perfect', then it's possible to create a convincing performance."

Last year Manze was introduced to The Perfect Houseplants, joining the adventurous jazz quartet to improvise around several Baroque themes and ground-basses, exploring the margins of free invention on his 1783 Gagliano violin. The combination is set to perform in Amsterdam next spring, a date that appeals to Manze's appetite for worthwhile musical challenges. "It was an extraordinarily liberating experience for me. As they reacted to what I did, I found it influenced what I was playing. The closest I'd ever got to that was in some of the freer moments in a concerto. They even wrote me in to some of their pieces, which stretched me in ways I've never experienced in Baroque repertoire."

Soon after we met Manze flew to Germany to perform Mozart's Fourth Violin Concerto with the Academy of Ancient Music. He invented his own cadenzas during the concert, their style reinforced by the player's close study of the composer's melodic language. "I have to force myself to devote some time each day to improvising and just meandering around on the instrument," he explains. "That's quite hard to do, but I always try to improvise in the style of the music I'm preparing."

The inch-worm process required to become sufficiently intimate with a composer's style and improvise freely in it does not invite corner cutting. Nor does it dovetail with the usual intense period of rehearsals followed by a concert performance and recording sessions. "Maybe this is a positive side of the tough time facing the recording companies and music industry in general. Nowadays it's not enough to say we have this repertoire of music, it's good, so let's record it. You have to believe strongly in the works you perform in order to get into the recording studio and for the record company to be able to sell the resulting disc. If I feel even one per cent unsure about a project, then Harmonia Mundi is content for me not to go ahead with it. That's the honest way to go."

Manze's latest release features sonatas by the 17th-century Italian violin virtuoso, Giovanni Antonio Pandolfi, an obscure figure whose work demands a free, spontaneous style of playing, the so-called stylus phantasticus. "With Pandolfi, as with so many Baroque composers," he explains, "it's a case of educating your instincts and then having the courage to follow them."

Phantasticus 17th-century Italian Violin Music, including works by Pandolfi Harmonia Mundi HMU 907213 Released: 12 May