When a tiny fringe venue in south London wowed the critics with its production of Stephen Sondheim's Pulitzer Prize-winning musical Sunday in the Park with George, the buzz quickly reached the composer-writer in New York. His confidants were also full of praise for the first London revival since the National Theatre's premiere in 1990, and Sondheim decided that he must see it for himself.
So, just after Christmas, he and his collaborator, James Lapine, slipped into the Menier Chocolate Factory, an industrial space in the backstreets of Southwark that was converted into a 190-seat theatre two years ago. There, they caught Daniel Evans playing the title character, Georges Seurat, the French pointillist painter. They liked what they saw. So did British audiences, and the production was a sell-out. David Babani, 28, the co-founder of the venue, found a string of backers for a West End transfer, and the impresario Cameron Mackintosh offered a favourable deal at one of his theatres to make it happen.
So, this week, Sondheim and Lapine are back, attending final rehearsals, just as they do for major revivals at national institutions. "Refinements, essentially," Sondheim says. "We thought it was extremely well sung when we saw it. It was moving and well cast. I was in tears. So James and I are not over here to criticise but to be helpful where we can. If there are scenes we can sharpen, we will give our two cents."
Whereas conventional stagecraft was used in the original show to recreate Seurat's 1884 painting Un dimanche d'été à la Grande-Jatte, the new version uses computer technology to "paint" the image on to the stage in vast strokes of colour, a technical tour de force of which Sondheim could not have dreamt. "I don't think that way, because it's not my generation. That kind of thing startles me, but it was magical," he says. He expected the wizardry to be even more effective in the larger venue.
He is thrilled at the transfer. Although he says that "some of the best experiences" he has had were with limited runs at the National Theatre or productions in the much smaller Donmar Warehouse, he evidently relishes a big commercial platform to win over those remaining Sondheim sceptics. For, as Ben Brantley observed in a New York Times review that coincided with Sondheim's original visit, the 76-year-old composer has long - though wrongly - been considered a cerebral composer, something of a cold fish emotionally.
Sondheim himself suspects that the "intellectual" tag stems merely from "a certain amount of literacy". He is intrigued by words - he even compiled magazine crosswords at one stage - and thinks that Britain has sometimes embraced his shows before the US because its literary traditions help audiences to appreciate them. "I don't want to put too much power in the hands of the critics, but Britain's a very literate country and there's a genuine love of language," he says.
Most holders of assorted Tony, Grammy and Academy awards would have developed a tough skin on the back of such honours, but not Sondheim. It still matters enormously to him that not everyone loves his work. "One of the nice things about a revival is that perhaps those people who didn't like it the first time will get a chance to see it again, particularly with a piece as elusive as Sunday..., which is dark and unusual. It's certainly not like other musicals. Sweeney Todd was loathed in London at first. It got dreadful reviews and lasted only three months."
That hurt, particularly as Sondheim has been an Anglophile since his youth. "It was my love letter to England, and I felt like a spurned lover. It really bothered me. Then, when it was revived at the National Theatre [in 1993], suddenly the general response was positive."
Sunday in the Park with George, which opened on Broadway in 1984, was his first collaboration with Lapine, and his first show since Merrily We Roll Along had been panned three years earlier. It takes as its starting point Seurat's aforementioned painting, Un Dimanche d'été à la Grande-Jatte, and creates a story around the people depicted in it, centring on Seurat's mistress.
Some have taken the obsessive artist George in the piece to be Sondheim himself, but the composer dismisses the notion. "I empathise with George simply because I empathise with anyone who does the hard work that art implies. So many people who are not creative artists don't understand that art is hard work. It's one of the things I feel passionately about. That's where my identity with George comes in most - how hard it is to write songs."
And it is getting harder all the time, he says. "The more you know, the less you know."
At present, he is trying to finish Bounce, a musical comedy about American enterprise that he began years ago. It deals with two brothers across half a century, looking at both the creativity and the hype of his native country. It sounds unlikely to do anything but confirm Sondheim's reputation as the thinking man of musicals, but it has been panned in try-outs in Chicago and New York. "I'm doing a final rewrite now, hope to get it on next year, and if not, then not. I've spent too much time on it."
Whether it is completed or abandoned, he will then find a new project, for fear of boredom, and of losing energy and confidence as age creeps up on him. A film version of Sweeney Todd is also on the cards.
Sondheim feels that it is not his cleverness alone that has won him enemies. He suspects that the dislike of Merrily We Roll Along, a collaboration with Hal Prince, was partly the consequence of their successful partnership on shows such as Follies and Company. "We were mavericks, but we made a decent living. It's all right if you're a maverick in a cold-water flat, five storeys up, with a baby crying. Or it's all right to be popularly successful, to be thought of as kitsch and make money and earn everybody's contempt. But to try to do original stuff and have some success irritates people," he says.
The US still hasn't enjoyed a good professional production of Merrily... By contrast, almost all of his shows have received first-rate stagings in Britain, even if not all are as well known as the productions of his immediate predecessors, Rodgers and Hammerstein and Cole Porter.
In fact, Sondheim himself would rather watch a play than a musical any day. "There's more variety and, generally, much more substance. If you look at the musical over the last 50 years, how many do you want to see again? Compare that with how many more plays."
So, for his stay in Britain, which he believes still outclasses America when it comes to productions of Shakespeare and other classics, Sondheim has an impossibly long list of productions he wants to catch. The National Theatre is top destination, and he wants to see his friend Judi Dench in Hay Fever. When we discuss the new David Hare translation of Maxim Gorky's Enemies at the Almeida, he promptly adds it to his list.
Curiously, mathematics, rather than music or literature, was his passion when young. "Math was like candy to me, so mesmerising," he says. Yet, thanks to the influence of his great mentor, the lyricist Oscar Hammerstein, he studied the liberal arts.
Sondheim met Hammerstein after his parents divorced and he and his mother moved to a farm in Pennsylvania, close to where the great librettist lived. The area has long been a favourite of artists and writers, which was another draw. "She wanted a place in the country, she liked celebrities, and she wanted me off her hands. She knew the Hammersteins slightly and they had a son my age. I osmosed myself into the Hammersteins and they became surrogate parents."
The move was "as crucial as crucial can be" to everything that happened to Sondheim thereafter. "There was a part of me that responded to theatre, and Oscar saw in me somebody he could pass his knowledge on to. He'd got a sponge. I was a perfect age - in my teens - and took in everything. But I've often said, glibly, that if Oscar had been a geologist, that's what I would have become."
Stephen Sondheim is, it seems, modest to a fault and reluctant to talk about himself. Though he has penned some classic songs, including "Send in the Clowns", he insists that he has not led a terribly interesting life. "There's work and then there's friends. I don't travel as much as I wish. I'm not a very colourful figure," he says. "I'm a half-empty-glass person. I'm generally a worrier."
He worries when he writes that it all sounds "old hat", just as what went before sounded old-fashioned to him when he was young. Yet the legendary American critic Frank Rich described Sunday in the Park with George as "the first truly modernist work of musical theatre that Broadway has ever produced".
Sondheim explains: "I like to try things that haven't been tried before. If I do something I've done before, I bore myself. It's much more fun to write when you're somewhat scared than when you feel absolutely on top of it."
'Sunday in the Park with George' is previewing at Wyndham's Theatre, London WC2 (0870 060 6633) and opens 23 May for a limited season. Stephen Sondheim and James Lapine discuss Seurat and the show at the National Gallery before Friday's performance. Call 0870 040 0003 for ticketsReuse content