Swift, who kicked off the UK leg of her 'Red' tour at London's O2 Arena on February 1, looked surprised when she saw the unknown man behind her. She continued her performance as the man was escorted off the stage by security, reported Ace Showbiz.
"It was an extraordinary breach of security. I couldn't quite believe what I was seeing. It happened during the final song of the concert when Taylor was dressed as a circus ringmaster.
Swift brought her collaborator and friend Ed Sheeran for a live performance of his hit single 'Lego House'.