Surveyors have said the ceiling of the Apollo Theatre is "sound" after 80 people were injured, seven of them seriously, when sections of it collapsed on the audience during a packed show.
Around 10 square metres of plaster from the Grade II-listed West End theatre plummeted on to the stalls below, dragging a section of the balcony with it, striking members of the audience and filling the theatre with clouds of thick dust.
More than 700 people were inside the Apollo - which was 45 minutes into the National Theatre's performance of The Curious Incident Of The Dog In The Night-time.
Boris Johnson praised the emergency services' 'exemplary' coordination, but said it was too soon to know the cause of the collapse.
"Another split second, and instinct took over. There was no need for an alarm or a call to evacuate..." an eyewitness account.