Opera singer Marie Arnet had no time for stage nerves when she stepped into the main role in a big production with just six hours' notice.

Marie, 28, was contacted by desperate officials from Glyndebourne Opera House near Lewes after illness claimed not only the lead singer but also her understudy.

Her last-minute performance saved the opening night of The Marriage Of Figaro on Monday and prompted rave reviews and a standing ovation from the entire cast and audience.

The problems began when Colette Delahunt, the principal singer for the major role of Susanna, contacted opera staff at lunchtime to say she had laryngitis and would be unable to perform that night.

With understudy Tamsin Coombs suffering from a throat infection, the opening night was under threat.

Organisers were left with the nightmare task of trying to find someone who not only knew all the Italian to the three-hour epic but was also available at such short notice.

They turned to Marie, who had worked as understudy for the same role during the summer production at Glyndebourne.

She agreed to help out and immediately drove down from London for an emergency rehearsal before the production began at 7pm.

Marie said: "I didn't get the call until lunchtime so I didn't have time to get really stressed and, because the cast was so supportive, I was able to relax and really enjoy the performance. It's a wonderful role to sing."

Jo Townsend, spokeswoman for Glyndebourne, said: "It was unbelievable to lose both Colette and Tamsin. I can't remember another incident when both principal singer and understudy fell ill at the same time.

"We were just lucky Marie had worked so hard to learn the role in the summer and she was available."

Mike Howard, music critic for The Argus, was among those who watched the opening night performance.

He said: "Marie was superb. It was an astonishing thing to do and very brave at such short notice.

"She is certainly a singer to look out for in the future."

Glyndebourne Touring Opera is confident Colette Delahunt will recover in time for the next performance on Saturday.

There will be a further three performances at Glyndebourne before the production goes on national tour.