Benjamin claims they're still alive, and perhaps better off, inside that hill, where the "piper" leads them after the minister fails to pay him for exterminating the rats, but one can't help but wonder how much oxygen they're getting.

"Written on Skin", his next opera and again a collaboration with British playwright Martin Crimp, will have its premiere at the prestigious Aix-en-Provence festival in France in July.

But despite its provocative title, and the unsettling nature of his first opera, Benjamin, 52, swears up and down nothing happens that is nearly as nasty as the title might suggest.

"People I've mentioned it to, particularly women, go 'phwew', as if it's got something quite erotic about it," he said in a recent interview at his London home, in a leafy neighborhood, with an environmentally friendly Toyota Prius hybrid parked in the narrow driveway outside.

A retrospective of his music this weekend at London's Southbank Centre is the occasion for the chat, the fact that he is one of Britain's leading composers is the reason.

"But the 'skin' we're talking about is parchment, on the whole," Benjamin continues. "Because it's the story of an illuminator entering the kingdom of a lord in the 13th century in Provence, hence the premiere in Aix, and the lord's wife becomes interested in him and trouble ensues, of a pretty extreme kind, eventually."

More than that he's not giving away, at least not in this interview at his home where he has a grand piano in the living room, and American soprano Renee Fleming's latest CD on his stereo. He does briefly produce a copy of the score, as if to prove that a composer renowned for taking his time getting his notes on paper has done the job, long before opening night.

"I wrote 95 to 100 minutes of music in 26 months, and fully scored as well, so when the last note was written the piece was completely finished. So statistically I am accelerating," he laughs. "But I still find it very hard. At least with opera, the blockages don't last months, they last days or weeks."

And what style of music would that be, for a composer who, despite his comparatively young age, is about to have a retrospective that is a London 2012 Festival countdown event -- counting down, of course, to the Olympics which start in July?

Is it in the category of music which goes by the ghostly, or perhaps sci-fi-sounding name "spectral", referring to compositions that emphasize tone color over harmony, melody and all that old-fashioned stuff? That's how Benjamin's music is described on the Internet, but he is having none of it.

"I don't like the idea of joining any groups or being filed under any particular drawer. I think your job as a composer is to be independent...I am, after all, from this country and I believe in independence, being outside and doing your own thing."

Music lovers can hear a whole weekend of Benjamin's "own thing", which is not a huge body of work, from his seminal orchestral piece "Antara" for chamber ensemble and electronics on Saturday, to his later "Palimpsests" for full orchestra on Sunday, with music of his hero, the late Hungarian composer Gyorgy Ligeti, thrown in, at Southbank. But don't go expecting to hear "Written on Skin". Not a peep until July.

Here's what else Benjamin had to say about his apprenticeship with France's mystical and birdsong-loving musical giant Olivier Messiaen, how he's yet another composer bowled over by movie director Stanley Kubrick and his use of music in films and why even if you've never heard of Benjamin or anything he's written, he suggests you open your ears:

Q: Messiaen was your main teacher and you had a very productive apprenticeship with him in Paris in the 1970s. Apparently he helped you to avoid falling into the clutches of the Darmstadt school of music, which with its formalism and advocacy of 12-tone music -- rather than lovely melodies -- produced pieces that, for some people, gave music a bad name.

A: "Messiaen said break away from Darmstadt...I'm glad I was 20 years old and I didn't feel the obligation to become a Darmstadt-type composer. And it has to be said that it only really lasted in its tremendous pulling power for about a decade, if that...But Europe had been through the worst catastrophe in a thousand years, so some things had to be examined from the root. Seeing in an abstract way was a noble thing to do but it led to a form of music that was too esoteric and that became a form of really horrid academicism quite quickly."

Q: So Ligeti, who did love a tune, and Kubrick, who used some of his music for "2001: A Space Odyssey" and other films, were more your style?

A: "Apart from (Disney's) "Fantasia", his (Kubrick's) are the only films that really use music in a dignified and grown up way. I like the way he choreographs his apparently spontaneous narratives to music, literally. In "The Shining" the editing and the actors' words are all inserted and timed according to the music underneath. It gives the feeling of being spontaneous and natural but it's a ballet, in fact."

Q: Why should anyone who thinks music began and ended with Pachelbel's "Canon" come to your retrospective?

A: "The world changes, music changes, music has always changed, music will always change. Not every piece written is a glowing masterpiece...but if you're sufficiently curious you come across some amazing pieces which will speak to you, if you have an open mind and ear."

(Editing by Paul Casciato)

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