Imelda Staunton's musical 'Hello, Dolly' has been postponed so that she can film 'The Crown'

Producer Michael Harrison told The Daily Mail's Baz Bamigboye: "Regrettably, we've got to postpone 'Hello, Dolly' — but she'll be back.

"We're still doing it. But we've just got to pick it up when Imelda's schedule allows."

'Hello Dolly' was due to start rehearsals in July, with performances slated to begin on August 11 at The Adelphi in London.

Michael added: "Who knows what the West End landscape will be like when Imelda's ready? If we can't get the Adelphi back, we'll play somewhere else — and make the announcement in due course."

The final series of the crown is due to film next year and Peter Morgan previously revealed he decided against making a sixth season because there "has to be distance" between real life and the show, although he had initially sketched out storylines for further episodes after that.

He explained: "You can't fully examine incidents that happened yesterday. There has to be ten to 20 years' distance. And in some instances much longer."

Peter promised the final series will be "explosive" and will culminate with Britain entering the new millennium.

However, the showrunner admitted he would like to visit the royal family again in five to 10 years time, but to examine a different period.

He said: "I don't know yet, but I might go further backwards in time, perhaps before this Queen."

Meanwhile, Imelda recently admitted she is "genuinely honoured" to be following in the footsteps of Claire Foy and Olivia Colman in the role.

She said: "I have loved watching 'The Crown' from the very start. As an actor it was a joy to see how both Claire Foy and Olivia Colman brought something special and unique to Peter Morgan's scripts. I am genuinely honoured to be joining such an exceptional creative team and to be taking 'The Crown' to its conclusion."