Westminster Council has said that the collapse of the ceiling of the Apollo Theatre in Shaftesbury Avenue last December was caused by the deterioration of century-old cloth and plaster ties holding up timber frames.
The incident during the Curious Incident of the Dog at Night Time injured 80 members of the audience when 10 square yards of plaster plummeted on to the stalls below, and forced the closure of the grade II-listed theatre.
The ties, made of hessian and plaster of Paris, were used to lash together timber frames to support the suspended ceiling and had been in place since the theatre opened in 1901.
The Apollo will re-open this week for the first time since December 19.
More top news
The hospital where the Duchess of Cambridge is due to give birth has had a superbug outbreak.
The London Marathon brings together thousands of people raising money for charity - not to mention some rather unusual costumes.
Planning on going to the London Marathon tomorrow? Read our handy guide first!