Engineers are trying establish why part of a plaster ceiling collapsed at a central London theatre injuring 76 people, seven of them seriously.

A large section of ornate plasterwork at the Apollo Theatre on Shaftesbury Avenue, fell on to the audience during a production of The Curious Incident Of The Dog In The Night-Time.

London Fire Brigade said a section of the theatre’s ceiling collapsed on to the audience who were watching a show. The ceiling took parts of the balconies down with it.

Steve Halcrow, executive director at FPDC, said: “It is important that the decorative features of historic buildings are maintained carefully using contractors employing craftsmen qualified in fibrous and solid plasterwork.

“We strongly advise that specialist plasterwork in historic buildings, particularly on ceilings at high level, are surveyed regularly, cleaned and, where necessary, make sure that any necessary repairs are undertaken to protect the integrity of plasterwork and ceiling structures.

“Fibrous and solid plastering in historic buildings is a specialist sector within the plastering profession. The technical teams from FPDC and AIS provide expert advice and many of our members carry out inspection and repair services for fibrous and solid plasterwork. Ceiling safety certificates are also available to building owners.”