It's a miracle that any opera ever gets performed He was launching the new season, but could not restrain himself from responding to questions about last season's rare revival of Robert le Diable. It was one of the 19th century's favourite operas, a work of unusual spectacle, but its composer Meyerbeer is more familiar in history books than in performance these days. Sir Antonio drew our attention to the catastrophic series of cancellations and substitutions that preceded the first night of the production. The production was postponed to permit the Peruvian tenor Juan Diego Florez to take part. Florez then pulled out, deciding that the role was too heavy for his voice after all. Another star, Diana Damrau, cancelled when she became pregnant, and was replaced by an American singer, Jennifer Rowley. Only a week before the first night, it became apparent that Rowley simply wasn't up to the role. She was dismissed. Finally, the role was taken by Patrizia Ciofi. The whole thing came very near catastrophe - opera buffs will appreciate the difficulty of finding a soprano who can step in and sing the lead in Robert le Diable at a week's notice. Sir Antonio gave way, in retrospect, to exasperation. There's something about this generation of singers, that they are weaker in their bodies or don't care. I don't know what it is, but it's something that is very, very frustrating for me personally. Pappano said that Placido Domingo, from a previous generation, "would have to be on his deathbed" before he'd cancel. Opera is an extraordinary thing, and its triumphs rest, like no other art form, on the physical and musical capacities of very rare individuals. A really great voice is not a common thing, and only rarely appears connected to a great musical intelligence. A great voice may appear, connected to a great musical intelligence, but they turn out not to know what you hoped to put on, or not to like Janacek one bit. Or they fulfil every single one of these criteria, and, amazingly, happen to be available; and then they come down with a cold. Most operas have at least five or six main parts that can't be skimped on. It is amazing, when you come to think of it, that an opera ever gets performed. There are just too many things to go wrong. But it's surprising that Sir Antonio gave way to such irritation, because the Opera House is going through a glorious phase. Tony Hall, who was the chief executive from 2001 until leaving to become the BBC's director-general, has been a triumph. Covent Garden has undertaken hugely successful outreach programmes, getting big audiences through cinema broadcasts. There was one memorable week when one of its broadcasts outsold Skyfall. Pappano himself has been a very successful and highly visible music director. The house has developed singing talent, in the main house and in the studio theatre, and, very notably, has established an excellent record in commissioning new operas. Three new operas in the past decade have been huge successes - Thomas Adès's The Tempest, Harrison Birtwistle's The Minotaur and George Benjamin's superb Written on Skin, currently packing in a young and engaged audience. That is a new thing. If the opera house could move from promoting English composers to mounting new work by world composers, it would make the final shift from a museum to a centre of living culture. It has not yet staged the defining operas of the past 40 years by Ligeti, Messiaen or John Adams. The journey of transformation may be just beginning. Does it matter? Opera, surely, is an expensive minority interest that hardly touches anyone's lives. But to have a superb institution at the head of national cultural life, at the top of its game, transforms everything. It makes London seem that bit more exciting. I can understand Sir Antonio's irritation at changing manners among singers and frequent cancellations, but he should perhaps shrug, and understand what a great moment he has helped to create. One suggestion: as the music director, he might like to ask singers to come earlier, and hang about the city and the opera house a little more. I fear that all that transcontinental flying, with countless bugs flying about in dehydrated air, is at the root of his little problem. I felt so happy when I heard about Lady Gaga's wheelchair. She has been obliged to cancel much of a tour after developing synovitis, but has made the most of a bad situation. She has let it be known that she has commissioned a wheelchair with a leather seat and back, and plated with gold by jewellery designer Ken Borochov of the label Mordecai. Some people really know how to behave like stars, I must say. Not for Lady Gaga the falling out of nightclubs and telling all to redtops. No whiny appearances on reality TV shows. Just wondering out loud how she can pimp up anything that seems to be required of her by asking a top designer to cover the whole thing with gold leaf, and then socking a sunshade on top. Surely, that's what we want from our stars. We don't want them to be just like us, and to be glimpsed hoiking their Waitrose ready meals into the back of the Toyota Prius. We don't want them to wonder out loud about whether now is the right time to have a baby or hear about their difficulties with weight loss. We want them to live, magnificently, behind massive castle walls, to spend their time lolling on leopardskin chaises longues stroking pythons, being drip-fed beluga, and to be wheeled about, when peaky, in gold-plated wheelchairs. What do you mean, you didn't sign up for that? If it wasn't in the job description of International Megastar, it certainly ought to be.