Pupils from Hayle were in the building next to the Apollo Theatre when the ceiling collapsed last night.
Year 11 pupils from Hayle Community School were enjoying a performance of Les Misérables in the West End of London when plasterwork from the ceiling of the adjacent theatre fell on the audience, injuring up to 80 people.
The 40 pupils were unaware that 10 square foot of ornate plasterwork collapsed during a performance of The Curious Incident of the Dog in the Nigh-Time.
The group, accompanied by assistant head teacher Mr Graham, were informed about the unfolding drama during the interval, when they were asked not to leave the auditorium as the foyer of their building was being used to treat casualties as they emerged from the Apollo Theatre.
Mr Martin, deputy head teacher, said none of the pupils were caught up in the incident.
“They were oblivious to what happened outside. At the interval a theatre manager came on stage and said there was an incident happening next door.
"They all got their phones out to check what was happening.Everyone was kept in the auditorium and the show continued as normal. They didn’t see or experience anything."
The pupils then exited the building through the back of the theatre.
The school's three-day trip to London takes place around this time every year- when pupils are taken to see two West End shows.
Mr Martin added that the pupils were all in high spirits and were looking forward to a shopping trip today in Oxford Street.
The pupils will travel back to Cornwall this evening.