The Events Research Programme ran test events at sporting, music and arts venues to assess the safety of large gatherings during the pandemic.
In a statement the group, which also includes musician Peter Gabriel, theatre producer Sir Cameron Mackintosh and music industry trade body Live, accused the Government of “making it impossible to plan for any live entertainment business” by not sharing their findings.
Live shows as part of the scheme have included the Brit Awards, music event Download Festival and a snooker tournament at Sheffield’s Crucible Theatre.
“These events have been a huge success, according to the Government itself in various press reports, showing that with proper precautions in place, live events at full capacity can go ahead safely,” the statement said.
“But the Government chose to keep the live entertainment industry under severe restrictions from June 21, while allowing parts of the economy that have not been subject to similar scientific studies, including hospitality, public transport and retail, to operate.
“The Government has also refused to publish the results from the first phase of the Events Research Programme, despite saying that it would do so on numerous occasions.”
Last week composer Lord Lloyd-Webber rejected an offer from Prime Minister Boris Johnson for one of his West End shows to be included in the pilot scheme for live events.
He said in a statement on Thursday: “Last week I rejected the Government’s invitation for Cinderella to be singled out as a last-minute part of the Events Research Programme.
“Today, with a range of voices from across the theatre and live entertainment industries, we are forced to take it further.
“We simply must now see the data that is being used to strangle our industry so unfairly.
“The Government’s actions are forcing theatre and music companies off a cliff as the summer wears on, whilst cherry-picking high-profile sporting events to go ahead.
“The situation is beyond urgent.”
The group also called for a Government-backed insurance scheme for live events, new rules around quarantining for productions where someone tests positive for coronavirus, and clearer guidance about how they will operate going forward.
The statement also said future pilot events, which include plans to let 60,000 fans into Wembley for Euro 2020 matches, are “little more than a way of allowing certain high-profile events to go ahead, primarily large-scale sporting events, while keeping the rest of the sector shut”.
Sir Cameron said: “Having been forced to close our theatres twice last year, the second time after the Government encouraged reopening for Christmas, losing further millions as a result, a joint insurance scheme to protect us against another enforced closure is vital.
“Along with most of the commercial theatre, we have had absolutely no direct financial help, either for our productions or the upkeep of our historic theatres.
“Opening without any sort of protection is impossible for many producers, live event organisers and theatre buildings across the country.
We understand a delay to full reopening is challenging for live events but we are helping our creative industries and sporting bodies through it
“Having contributed huge amounts of money to the exchequer over the last few decades, the theatre desperately needs to be supported in its hour of need or the Government will be responsible for the disintegration of one of this country’s most priceless and irreplaceable assets, after centuries of being the envy of the world.”
Culture minister Nigel Huddleston said earlier this week that if there were “major concerns” about the results of the research programme “we would have made sure that information was in the public arena”.
Speaking in the House of Commons, he added: “Some of the initial data points were already announced by the secretary of state back in May but the report needs to be comprehensive, it needs to be reviewed by a large number of stakeholders in Government, we will be releasing it very soon indeed.”
A Government spokeswoman said: “We understand a delay to full reopening is challenging for live events but we are helping our creative industries and sporting bodies through it.
“We have made a record £2 billion of support available for culture and £600m for sports, on top of billions more through other government schemes.
“Our ongoing, groundbreaking Events Research Programme is gathering important evidence to help get all live events, including theatre shows, festivals and gigs, fully back up and running once it is safe to do so.
“We will publish the results of the programme before the move to Step 4, as we have always promised to. This aligns with the publication commitments for the other road map reviews.”