A video of two pranksters spending the night inside the National Theatre has raised concerns about its security.
In the video, YouTuber Ally Law and another male are seen walking on lighting rigs and climbing up inside the Olivier Theatre’s flytower.
At one stage they are approached by a security guard, who leaves them alone when they claim to be rehearsing.
Liz Fosbury, the National’s chief operating officer, was said to be “shocked and concerned” by the video.
“The safety and security of everyone at the National Theatre is of the utmost importance,” she said in a statement published by The Stage.
“We were shocked and concerned that two intruders recently put themselves at great risk by gaining unauthorised access to a restricted area of the building.
“We would like to reassure audiences that we have taken immediate action to further strengthen our security.
“We liaise with the police on an ongoing basis and we are working closely with the Met[ropolitan Police] following this incident.”
In the video, the two males are seen gaining entry into the building through an unlocked door that gives them access to the set of the National’s production of Follies.
They are then seen leaving the London complex the following morning after spending the night sleeping backstage.
Freelance theatre director Rafaella Marcus made light of the incident on Twitter, calling it “the most socialist thing to happen in the Olivier for years.”
Yet others took a dimmer view, among them choreographer Darren Carnall.