“FAST, spidery, brilliantly rhythmic,” says Melvyn Tan with a grin, scurrying his fingers across the sofa to mimic the sound of the music he’s describing. The 59-year-old pianist is talking about a new solo piece currently being written for him by the composer Jonathan Dove; he’ll premiere it at the Cheltenham festival in July and record it later this year as part of his 60th birthday celebrations. Having already received a few sizeable chunks of the score, Tan seems delighted: “it’s a little bit jazzy, a little bit Keith Jarrett. Very articulated, light, accented… I suppose you could call it virtuosic, but not in any heavy way.”

All of which applies directly to the pianist’s own style of playing, whether in the classical fortepiano repertoire that made his name back in the 1980s or the poised and supple modern-instrument voice he later developed in Messiaen, Schumann, Chopin and more. There’s a gracious, lucid and holistic quality to the way Tan thinks about music; it informs how he researches scores and builds programmes just as much as how he performs. Some readers might remember the marvels he revealed at the 2011 Edinburgh International Festival when he interwove the music of John Cage and Domenico Scarlatti. On his birthday in October this year, he’ll give a concert at the Wigmore Hall in London exploring teacher-pupil relationships between Beethoven, Czerny and Liszt — all of whose music he approaches with classical-era clarity and elegance rather than Romantic-age showboating.

“I don’t have a huge sound,” he readily admits. “I’m not a Brahms player because I’m just not suited to it physically.” Sipping a sophisticated-looking tea with his legs nimbly folded underneath him, it’s easy to see how his spry and compact build matches the sound he makes. But in any repertoire, no matter how hefty, Tan always finds a way of letting the light through.

“I suppose I tend more toward French music than Brahms anyway,” he reflects, “probably because I learned with French professors at school.” Tan was 12 when he moved from Singapore to study at the prestigious Yehudi Menuhin School in Surrey, where one of the regular visiting teachers was the formidable Parisian theorist and pedagogue Nadia Boulanger. “She was terrifying!” he giggles. “A grey-haired lady with thick glasses and a grey flannel suit. Us kids didn’t really have a clue how important she was and we’d sit at the back and muck about, but she never missed a trick. All of her masterclasses were conducted in front of the entire school. Every piano pupil had to play a Bach prelude and fugue and she would make us sing one of the fugue voices while playing the other parts. Nobody could do it — not even the teachers. Except for her, of course!” Another giggle.

Boulanger was fearsome, he says, but never mean. “Those classes were daunting but she only wanted us to do our best. Still, you couldn’t put kids through that now. It would be too much pressure.” He talks about the hothouse atmosphere of the Menuhin School at that time, how “a lot of the staff were competing with each other through their students. Some of my contemporaries fell by the wayside because of the pressure.” But he says he was happy there, having come from an “extremely protected” upbringing in Singapore and found a degree of liberation in living with fellow students and playing chamber music all day.

Yet it was when he went to the Royal College of Music and discovered early instruments almost by accident that Tan started to discover his distinct voice as a player. “I took up fortepiano because everyone at college had to have a second instrument, and I more-or-less figured it out as I went along. People thought I was mad: ‘why do you bother with that strange dinosaur instrument?’ they’d ask me. I was convinced musically that it was the right sound for me, but I had to work hard at mastering it and convincing people.”

Then came the recordings that launched his career: the complete Beethoven piano concertos for Virgin Classics with Roger Norrington and the London Classical Players. These period-instrument performances were bright, spirited, feisty, nuanced; listening to them nearly 30 years later, there’s still a joyous freshness and verve that speaks of the adventurousness shared by Tan and Norrington. “Oh yes, that throw-away thing Roger had,” Tan agrees. “And such wit. Such wit!”

Why, then, does Tan now perform almost exclusively on modern Steinways? “Ah,” he replies with a mischievous glance, pausing as if to decide whether to come clean. “Because it is more practical. Yes, really! I don’t have to bring my own piano and tuner everywhere. Notes sticking, pedals not working… I grew so tired of it!” Besides, he adds, “modern Steinways are built with such light action nowadays that it’s almost like playing a fortepiano. The lightness works for Schiff, it works for Uchida, it works for Murray Perahia, it works for me. Only Brendel liked his keyboard really heavy.”

But the shift in focus was more than practicality. Tan is drawn to repertoire and artists that require modern pianos. In 2006 he played Messiaen’s monumental Vingt regards sur l’enfant-Jésus for the first time — “I was afraid of learning it because Steven Osborne’s recording had just come out and ooft! I didn’t think I could ever compete” — and he says that experience changed the way he plays. “I’m more confident now. With a piece like that you can’t even contemplate feeling nervous. You have to sit down and throw yourself into it, and that has made me more incisive ever since.”

Now his repertoire roams from prepared-piano John Cage (“when I flew to Singapore I was ready to explain to some security officer why I had a little box of nuts and bolts in my luggage”) to Ravel’s G Major Piano Concerto with an orchestra of Chinese instruments. This week he visits Edinburgh with the Bruckner Orchestra Linz — a band explicitly trained for the rich, Romantic soundworld of its namesake.

Another recent shift has been Tan’s rekindled relationship with Singapore. In 1979 he was faced with a choice between two-and-a-half years of military service or imprisonment; he found a third option and became a British citizen, but the Singapore authorities warned he would be arrested if he ever tried to reenter the country. “I didn’t take the risk for more than 30 years, but in 2006 my parents asked me to see if I could come back. The arts scene was burgeoning, there were wonderful concert halls and conservatories and I dearly wanted to give something back to the young people of my country.” He was met off the plane by officials and had to argue his case in court, but he now he gives regular recitals and works with the country’s orchestras and conservatories. “It feels like something has been put right,” he says. “In some respects this whole birthday year thing is just a marketing ploy, but actually it is a good moment for me to reflect and reboost. I’m busier than ever and I’m still learning like mad. I like that!”

Melvyn Tan plays Beethoven with the Bruckner Orchestra Linz at the Usher Hall, Edinburgh, on Sunday