We met on a Monday morning. The previous day's papers had revealed that his latest novel, Monsieur Renee, was number nine in the hardback bestseller lists. I reminded him of a play he had written in 1962 called Photo-Finish, in which the protagonist (whom he played) was an 80-year-old man, looking back at his life at 20, 40 and 60. At the time, the 41-year-old Ustinov had said, "If I live to be 80 I see myself as somebody full of wisdom, probably not being taken notice of by anybody, and probably quite content." So how did the reality of his age match up to the way he had anticipated it? "I've still got two years to go!" he pointed out, then added, "I feel I can talk with more authority, especially when I say, `I don't know.'"
Was he more content? "On the whole. I've got nothing to quarrel with, really. I don't store up anything because I write about it for the Courier in Vienna and the [German newspaper] Welt am Sontag. I occupy all sorts of functions I never dreamed of doing when I was younger. For instance, not only am I Chancellor of Durham University, which I enjoy enormously, I'm also President of the World Federalist Movement." As such, he attends meetings and conventions all over the world (the last big one was in Madras), promoting world peace and opposing nationalism.
He has recently been involved in the campaign to create a world criminal court, capable of judging those whose crimes extend across separate countries, or whose power prevents their crimes against humanity being punished in their own home states. So far, 150 governments have signed up to to support the idea.
But neither literature nor world peace were the reasons for Ustinov's visit to London. He was in town to supervise the dress rehearsal and concert performance of Richard Strauss's last, unfinished opera, The Donkey's Shadow, for which he has written a narration. He has also scripted new words for Saint-Saens' Carnival of the Animals, which he has performed on German TV and is taking to this summer's Verbier Festival. The Garmisch Strauss Festival has just heard him narrate a musical production of the Bourgeois Gentilhomme, and he's working on a new production of Beethoven's only ballet, Creatures of Prometheus, to be performed in Germany this December with the Latvian Chamber Orchestra.
We, though, were meeting to discuss another international cultural artefact - Ustinov's 1997 production of the Prokofiev opera The Love Of The Three Oranges, created for Moscow's Bolshoi Opera, which will be performed at the Coliseum in August. Ustinov loves Prokofiev. "He is a composer I understand very well, a very Russian composer. All the music critics said early Prokofiev, like this piece, was percussive, was brash. But when you work on the opera, you find wonderful, soaring, lyrical passages which are absolutely reminiscent of the Romeo and Juliet or the Violin Concerto to come."
In Moscow, the production was acclaimed as a triumph. "Of all the operas I have produced, this is the one I'm most pleased with," he said. "It's divided into two halves. At the end of the first half once could feel a kind of buzz in the audience. They were still guarded in their applause. Then after the second half it was really fantastic. They greeted it as they might have greeted the first American musical - it was a liberation. Isvestia came out with a headline, `Englishman saves the Bolshoi'. That I should be accused of being English there, of all places, struck me as being very paradoxical."
As one might expect from such a legendary raconteur, his trip to Russia provided him with a fund of anecdotes and bon mots. "I had a very brilliant designer who was also one of the most difficult men I have ever come across. He walked out of the production four days before the first night, very ostentatiously. Thank God my Russian isn't up to his because his magnificent exit was translated for me, so it lost rather a lot of its effect, and he'd already gone before I could react. What he said was, `You'll find I'm too expensive a toy to play with in this manner.' Isn't that a good line?"
The designer's set involved a number of computer-controlled, hydraulically operated bridges, which were meant to rise and fall, enabling the cast to be arranged at various levels across the stage. Unfortunately, they arrived late, then turned out to be better at falling than rising. As Ustinov recalled, "The cast refused to go on the bridge. So I, with my stick, went onto the highest level and faced the rebellious crew, like Captain Bligh. They applauded, but still refused to go on the bridge. Then one or two of the women started going on the bridges, and since they didn't fall down, more of them went up and began to chide the men for their cowardice. Then the men said, `Come down here and we'll show you what cowards we are.' Eventually, they all went up and the situation was saved."
There were many more stories, covering everything from hitching a lift on a Moscow boulevard, through to reminiscences of life in a suicide battalion, when he was posted to the White Cliffs of Dover before the anticipated German invasion of 1940. They were beautifully told and unfailingly amusing, but they were also a performance - a sign, perhaps, of a man who wished to control the information he gave out about himself, and the impression he created. Ustinov, reasonably enough, took mild offence when I put this suggestion to him, adding that the intention of his stories was to illustrate, rather than conceal. Later in our conversation, before another yarn, he remarked, "I'm going to amuse you now, though it's not my intention..." But the more we left the performances behind, the more the true Ustinov was revealed, and the more I warmed to him. He is a man of forceful opinions - his denunciations of the bombing campaigns against the Serbs, then at their height, were savage, his humour becoming far more barbed and far funnier as a result - but also, perhaps, formidable insecurities.
His father was a journalist who became the press attache at the German embassy in London, before spending World War II working for British Intelligence. The family arrived in Britain in 1921, just in time for Peter to be born in Swiss Cottage. He was their only child. "It's very awkward to be one side of a triangle," he recalled. "I'm told my father was jealous of me because my mother paid more attention to me than to him. He was not a very easy man.
Peter grew up as a precociously bright, hopelessly unsporting boy in a public-school system that suspected intellectuals and worshipped competitive team-games. His response was that of countless comedians. "I got out of trouble by making them laugh. That's probably where the whole nonsense starts from."
His upbringing left Ustinov with a lifelong mistrust of upper-class Englishmen, a gift for placating audiences with comedy, and a burning desire never to face the same financial insecurities that so dogged his father. "I've never really been interested in money," he told me, "except when I haven't got any." But I noticed that when he described how well he'd been treated by the Bolshoi, the first example he gave was that he had been paid in full, and on time. For the past half-century he has been constantly at work: writing, acting, directing, producing and campaigning - working for the fun of it, for the necessity of meeting expensive alimony payments, for the pleasure of affording his 58ft yacht. He may be forced to move slowly, but he has no intention of slowing down in any other respect. As he told me, when I asked him about life at the end of his eighth decade, "I still enjoy being alive."
`The Love of The Three Oranges' opens at the Coliseum, St Martin's Lane, London WC2 (0171-632 8300) on 7 August. A version of this article appears in the current issue of `Classic FM' magazine