Even in France, the country whose woodwind tradition is reputedly the best in the world, such a young appointment made waves. Leleux went on to top positions at the Bavarian Radio Symphony Orchestra and the Chamber Orchestra of Europe. He became a great soloist, an active chamber musician, a committed teacher, and he has recently been spending increasing amounts of his time conducting around the world.
"My aim is to embrace music with as large an angle as possible," he said. "Think about the renaissance: we should all be painting paintings, inventing instruments ... I think that being just an oboist is not quite enough."
But what an oboist he is. The sound he makes on the instrument is unmistakable: it is immense, voluptuous, dark and oily. His musical energy is alert and totally uninhibited. Last year he gave a breathtaking recital at Yester House, near Gifford, East Lothian, as part of the Lammermuir Festival. His Mozart was opulent and shapely, and his Britten - the Six Metamorphoses After Ovid - was ardent, playful and heaped with vivid character.
After the concert, an announcement was made that Leleux was to be artist- in-residence of this year's Lammermuir Festival. A huge cheer went up from the crowd: Leleux might not be as well known in the UK as he is in France and Germany, but the East Lothian audience clearly knows a good thing when they hear it.
After the concert I sat with Leleux in one of Yester's many plush drawing rooms to talk about the Lammermuir appointment, how he juggles his many musical hats and how he makes that famous sound.
"Well, I believe sound is basically a matter of intonation," he said, pouring two large coffees and settling back into the baroque upholstery. "You have to find the centre of a note in order to make it sound as smooth as possible. And you have to use your ears as carefully as possible to collaborate with the acoustic. I try to imagine a black room in which there is only sound, then make my articulation as soft and velvet as possible."
He talked me through a small masterclass in oboe technique, divulging trade secrets and all. "Don't make the vibrato too fast or narrow in the high register," he said, waggling his finger, "otherwise the sound becomes horrible and small. Try to play like a string instrument, using air like a bow. I almost never use my tongue to start a note; I begin just with air."
If this all sounds a bit technical, the bottom line is smoothness. It is the smoothness that tends to be the first and last impression of any Leleux concert.
Leleux learned his craft in France but now lives and often works in Germany. Traditionally, the two countries have cultivated hugely different oboe sounds; how does he navigate the musical dialects? He just shrugged at the question. "In Germany they say I have a more German sound than my colleagues, and in America they tell me I have a lovely American sound. It seems people are happy with my sound wherever I go!"
"Besides," he continued, "national stereotypes do not really hold true any more. Of course the sound a wind player makes is related to the language that he speaks" - he demonstrated, flitting from rotund German to nasal French to plummy English, really hamming up the character of each. "But we are all more international than ever nowadays. I speak a bit of German, a bit of English, some Danish, some Georgian because of my wife (the Georgian violinist Lisa Batiashvili)."
That said, the words of music remain important to him: he has made his own transcriptions of arias from Mozart's Don Giovanni and Die Zauberflote and has recorded them with Camerata Salzburg. "When I play the Mozart arias, it is so wonderful to read the words and think about their intention. Sometimes I wonder about putting words to all of the music I play. But that might take some time ..."
Leleux described the Lammermuir residency as "a wonderful chance to be an explorer". He looks for "something special" in programming, he said. "I am not interested in playing concerts for concerts' sake, and I believe contemporary music should be included in programmes like it was at the beginning of the 20th century or in Brahms's or Mozart's time. It is only recently that we play just the music of the past. It should be more mixed."
His Lammermuir programmes are duly mixed. In the opening concert he plays Strauss's Oboe Concerto with the Royal Northern Sinfonia; two days later, he gives an intriguing solo programme of music by Telemann, Bach, Anton Dorati, Silvestrini and Luciano Berio.
Later in the festival he teams up with some of Scotland's top wind players and tenor Ben Johnson for chamber music by Vaughan Williams, Poulenc and Dutilleux, and he ends his residency with Mozart's resplendent Gran Partita.
Leleux started playing the oboe at the age of six. "The instrument was about the same size as I was!" he said, with a laugh. "It is physically demanding, especially for such a small set of lungs, but if a six-year-old asked me about starting now I would say, 'Go for it'! You can't stop somebody who wants to do something at that kind of age. They must be supported."
Nearly four decades later, Leleux says the oboe is like a part of his body. "I had terrible pain in my back 10 days ago. I was moving from Paris to Munich and could not play for a few days. But after a couple hours of rehearsing at Lammermuir, the pain went away. Music is like a jealous woman; you can't leave her alone too long."
Francois Leleux is at the Lammermuir Festival from September 12-21.