The Edinburgh International Festival unusually begins this year not with a concert at the Usher Hall, but with an opera; and with Bellini‘s Norma, one of the great, grand operas; and with Cecilia Bartoli, one of the biggest opera stars in the world. The Festival Theatre is packed and it gets a standing ovation with many curtain calls, but is it as good as the response suggests?

The answer is no; there are some serious flaws. When Norma was announced with Bartoli nine months ago, some questioned whether she had a big enough voice to fill the Festival Theatre. Indeed, when Bartoli premiered this production in 2013, she chose the smaller opera house in Salzburg, and has chosen small opera houses on tour. The Festival Theatre is a much bigger challenge.

From the upper circle, the audience hear her first big aria Casta Diva, but it is fairly faint. When she first began to sing, even before her famous first aria, her voice sounded dry and underpowered, drinking water and using a hankie during the act.

As to her rendition of Casta Diva, it is also underpowered and unconvincing. Maria Callas, Joan Sutherland, Monserrat Caballe and Anna Netrebko have all sung it far better than Bartoli tonight. In fact, Bartoli herself sung it much better on her latest CD. Tonight, it was Casta Diva without the diva, and it inevitably clouds the opera.

To be fair to Bartoli, her voice improves in the first act and is better in the second, while her acting is consistently good. She is ably backed by a decent cast. Young Mexican soprano Rebeca Olvera sings a good Adalgisa, and John Osborn, a sweet young American tenor, sings Pollione well, although his voice wavers under pressure. The chorus sing and act well and the small orchestra I Barrochisti play beautifully under stand-in conductor Gianluca Capuano.

The production has other problems. Norma is set in ancient Roman, among temples and druids and high priests. This production, directed by Moshe Leiser and Patrice Caurier in the modern operatic style, updates it 2000 years to occupied France in the Second World War. Instead of a temple, we have a school room, instead of Roman soldiers we have French resistance fighters. The chorus do their best to act out this unlikely setting, and if you ignore the libretto, it makes dramatic sense. But being set in one room, Norma has come to resemble a social realist drama instead of grand opera.

Despite these flaws, Norma makes a good opening event for the International Festival, and the audience love it. Sadly, opera, which used to be the centre of the Festival, has become its poor relation, not least because of the cost of staging it. There are only three this year. Festival director Fergus Linehan has promised to improve the opera line up in future years, including using Scottish Opera, who are sadly missing this time.