When Monica Mason was appointed director of the Royal Ballet six years ago there were cheers all round — from the dancers, still reeling from the onslaught of Ross Stretton’s provocative directorship; from the board, anxious to bring stability and calm to an overwrought company; and from critics and public alike, who saw her as a keeper of the precious flame. If anyone was going to protect the Royal’s unique heritage, they argued, it would be the woman who joined the company as a dancer in 1958 and has remained there, in one capacity or another, ever since.

Now, inevitably, the honeymoon is over and for some, at least, her safe pair of hands is starting to look too safe. The announcement of the 2008-09 season, which opens on Saturday, was greeted with the most strident criticism that Mason has faced in her artistic programming. Timid and predictable, her critics barked. Too much looking back, not enough looking forward.

Mason doesn’t really do angry, at least not in interviews, so any defence of her decision-making is going to be delivered with impeccable good manners and a list of sensible reasons why. “I want to do new ballets,” she says, “but the way the Royal Opera House works means that we can only make two or three new works a season. Because of the number of performances — we do 135 a year — the programmes change more and we have to rehearse more. It takes more hours just to do the ballets we have; to make new ballets takes even more hours.

“If whoever takes over from me decides this system is completely mad, and they want to focus on six new works a year, the whole way of working will have to be redone; and that would be a matter for the board of directors and the box office.”

Back in the 1960s and 1970s, when the South African-born Mason was thriving as a dancer, the Royal wasn’t such a tight ship. In those days, she says, the company performed less (about 90 shows a year) and there was more time for creative endeavour. “It is a busier house now, and a more predictable house, I agree, but I’m not the person to change that.”

Yet just because Mason charts a steady course doesn’t mean that she isn’t effecting change. Already she has amped up the company’s “English” profile by appointing three home-grown principal dancers (Edward Watson, Lauren Cuthbertson and Rupert Pennefather) and named Barry Wordsworth as music director, thus filling a position long left to languish. More controversially she has appointed Wayne McGregor, the fashionably edgy contemporary dance-maker, as resident choreographer, a decision that has yet to be vindicated. She gave him the job after the premiere of his Chroma, a ballet, she says, that “hit the spot with 25-year-olds”.

“I think Wayne’s appointment is an injection of creative spirit into the company. I was very keen that we had someone who took a broad view of what goes on in this theatre and was able to guide young dancers wanting to try their hand at choreography.”

The 2008-09 season will feature world premieres from McGregor and Alastair Marriott, along with a revival of Michael Corder’s L'Invitation au Voyage (1982) and Kenneth MacMillan’s full-length Isadora, widely considered a failure in 1981 but now about to be reborn as a one-act ballet. “If, out of all the intriguing material Kenneth left us in Isadora, we can’t make an interesting hour I will be disappointed,” Mason says. “This is the kind of contribution I can make to the history of the Royal; whoever takes over from me probably wouldn’t dream of doing it.”

Other revivals include Will Tuckett’s Seven Deadly Sins, Christopher Wheeldon’s DGV and Mats Ek’s Carmen. But the backbone of the season remains the war horses — Swan Lake, Manon, The Nutcracker, La Bayadère and Giselle. So is it her job to run a museum company, endlessly recycling the big productions while paying homage to heritage whenever an appropriate anniversary pops up? “I don’t feel like a museum-keeper at all,” she says. “But it’s not as if we have 25 full-length ballets to call upon and very few choreographers now want to make a full-length. I have explored the possibility of commissioning one and decided against it; you are talking big bucks — a million plus — and it just hasn’t felt right.”

This year Mason, 67, marks her half-century with the Royal: “As I have a reputation for being the anniversary queen, it’s rather fun that this year it’s actually my own anniversary.” So happy is the board with her that it has renewed her contract to 2012, which means she will have had a decade in which to stamp her legacy. “I would like to think that with the appointment of Wayne I had a stab at the 21st century. But I am also trying to give people in their twenties the chance to experience some of the treasures we knew in the 20th century; and while the people who teach those ballets are still alive, we should be mounting them. There will be ballets done during my directorship that won’t be done again and some of them will be beautiful.”

Swan Lake opens at the Royal Opera House (020-7304 4000), on Saturday

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