The Government could allow Andrew Lloyd Webber to open his new production of Cinderella with a large audience as part of the Covid pilot scheme, after the impresario threatened them with legal action.

Theatreland was in despair as the Prime Minister confirmed their worst fears by announcing the four-week delay to a full reopening.

But Boris Johnson indicated that Cinderella could receive special dispensation, heading off a potential showdown.

Lord Lloyd-Webber told The Telegraph last week that he would open the show with a capacity audience "come hell or high water" and was prepared to face arrest for doing so.

"I’ve got colossal admiration for Andrew Lloyd Webber. The entire theatre sector is one of the great glories of this country. On Cinderella, I think we’re in talks with him to try and make it work, and we’ll do whatever we can to be helpful," Mr Johnson said.

The pilot scheme will allow certain events to go ahead with increased capacity audiences and fewer restrictions.

Lord Lloyd-Webber said: "My goal is, and will always be, to fight for the full and safe reopening of theatre and live music venues up and down the country.

"I was pleased and surprised to hear the Prime Minister mention Cinderella as part of his announcement today, but I can’t comment further on the proposed pilot until I know more about the scheme."

Theatregoers who have booked tickets for Cinderella performances from June 25 onwards received a message on Monday saying: "We’re working hard behind the scenes to make sure everyone gets to the ball."

Lord Lloyd-Webber’s rivals have received no Government assurances and one source said: "If they were to announce that some West End shows were to be able to open fully as a pilot, that feels very awkward. Everyone’s heads are going to explode."

Other theatre producers said they were in "despair" at the four-week delay to unlocking, likening the Government messaging to a West End farce.

London and regional theatres had pinned their hopes on a full reopening on June 21.

One of the year’s most anticipated productions is Hamlet at the Theatre Royal Windsor, starring Sir Ian McKellen. It was due to run from June 21-September 4 with full capacity audiences.

Its producer, Bill Kenwright, said: "This is the worst day I’ve known in the business. I despair."

Sir Howard Panter and Dame Rosemary Squire of Trafalgar Entertainment, one of the UK’s leading theatre owners and producers, said: "This delay is yet another bungle from a government that wouldn’t be given a single star in a review of its performance.

"The confusion and muddled messages are reminiscent of a West End farce.

"During the pandemic this Government has been fond of three-word slogans. Hands, Face, Space. Build back better.’ Today we ask them to consider a few more. ‘Open our theatres.’ ‘Enough is enough.’ ‘Let audiences in.’"

The Society of London Theatre and UK Theatre said the four-week delay "will have serious implications" for many theatres, with thousands of jobs "hanging in the balance".