Deep cracks have appeared in one of the huge angels etched into John Hutton’s west screen of glass panels at Coventry Cathedral after a major music event.

It has prompted concern that the increase in cathedrals hosting outside events, a big source of revenue, risks damaging some of the UK’s most important religious architecture.

The west screen, considered a 20th-century masterpiece, has 66 larger-than-life saints and angels designed and hand-engraved by Hutton. It was commissioned by the architect, Sir Basil Spence, whose monumental building incorporated the ruins of the 14th-century cathedral, which was bombed during the second world war.

Jennifer Alexander, a professor of architectural history at Warwick University, said the etched panels were groundbreaking when they were first revealed. “Nobody had ever done anything on that scale before,” she said.

The screen was damaged on 22 May, when the Illuminated Orchestra was setting up for its concert of “dark fantasy film music”. The ensemble regularly performs in historical buildings.

Its musical director, Kellija Moncaka, said the the damage was caused by a freak accident involving a ladder used to put up lighting.

“It was purely an accident of a gust of wind … when we were setting up,” she said. “I saw the cathedral staff cover up the screen straight after.”

Prof Louise Campbell, a leading authority on Coventry Cathedral, raised concerns about the damage with her colleagues.

“The cathedral has not publicised this, perhaps because it occurred during one of the events which bring in revenue, or perhaps because there was some failure of supervision,” she wrote in an email.

She told the Guardian: “The cathedral, in order to earn money, has events – not only its own events – but it hosts events from outside organisers, anything from pop concerts to drama. I’ve always been rather worried about the impact of these events. Clearly something went very wrong in May.”

She is asking for the cathedral’s events programme to be paused to review how to protect Hutton’s fragile work.

In 2020, another one of the huge angel panels was smashed during a burglary. Two men hurled a brick through it and made off with a charity collection-box.

She said a highly skilled engraver could reproduce the damaged Gabriel figure, but that the effect of repeated damage could become “a terrible mishmash.

“ If you weigh up what you earn from events against what you’re actually having to spend on putting right the damage, it’s crazy,” she said.

The cathedral’s acting dean, Canon Kate Massey, said: “We can confirm that a panel of the iconic John Hutton west screen was damaged at an event earlier this year. It was an unfortunate accident caused by a ladder being knocked against it and it was distressing for all involved. Coventry Cathedral is a much-loved building which sits at the heart of our city and community.

“Part of being a living cathedral means that it’s our joy and privilege to welcome people into the cathedral through a diverse and engaging calendar of services and events whilst caring for the priceless art that our cathedral holds. We have taken specialist advice and are looking forward to the panel being restored later this year.”