Something in the aria

For an opera company to lose one of its leading ladies just before rehearsals begin is unfortunate. To lose two is downright catastrophic. Nevertheless, this is the fate that has befallen the English National Opera's upcoming production of perennial Mozart favourite Cosi Fan Tutte.

The reason for this unhappy exodus is, however, the happiest of all. Both divas are expecting. Star sopranos Giselle Allen and Stephanie Marshall have both bowed out of their roles as fickle sisters Fiordiligi and Dorabella to nurture their new arrivals. But unfortunately for the ENO they discovered their happy news almost simultaneously, 18 months after being cast in Cosi.

Now ENO's put-upon casting director John Berry is struggling to recast the roles. He told the Evening Standard: "It really is a big headache.

Casting any Mozart role is really difficult - casting those roles at 18 months' notice is a challenge in itself.

"However, casting the two lead roles with two weeks' notice is well nigh impossible.

"I need to have two singers in place by the end of this week for the beginning of musical rehearsals - it is just rotten luck."

Both singers were unavailable for comment but Mr Berry said: "They are incredibly disappointed they can't do the production - but both are obviously thrilled about being pregnant."

Fiordiligi is "a notorious soprano role", said Mr Berry. "It has two big arias that require two or three different sorts of voices. You need somebody with nerves of steel."

Ms Marshall's part of Dorabella has different demands. "It is a high mezzo soprano role, out of the reach of some mezzos," said Mr Berry.

"When you put the cast together for an ensemble piece you try and do it extremely carefully, so each part complements the whole - but when you lose two singers at the last minute that all changes."

Despite the challenge of finding replacement singers in the next week Mr Berry said: "We've never had a situation where the curtain hasn't come up because we haven't found a singer - but it is now a bit close to the wire and we need a real stroke of luck.

"We still haven't found the right person for Dorabella."

Tickets for Matthew Warchus's acclaimed production are already on sale and the first Coliseum performance is scheduled for 26 May.

However, the ENO may have found at least a partial solution: young Irish mezzo soprano Anne Marie Gibbons - who was due to understudy the part of Fiordiligi - seems likely to be brought off the bench to open Cosi Fan Tutte.

Mr Berry said: "We're incredibly lucky to have Anne Marie on our young artist programme - she is very, very talented."