Discover the LSO, Classic FM's Orchestra in the City of London, with a biography, news and music to play and download.
The human rights activist strode onto the stage to protest about the conductor's support for Russian president Vladimir Putin.
The opening night of the London Symphony Orchestra's Berlioz series at the Barbican was disrupted on Thursday by Peter Tatchell, who protested against Putin and his support for the anti-gay laws in Russia.
"Valery Gergiev is a friend, ally and supporter of the Russian tyrant Vladimir Putin, whose regime is arresting peaceful protesters and opposition leaders," he told the audience. "Gergiev defends the new homophobic law that persecutes gay Russians. He sided with Putin against Pussy Riot. I ask you to oppose tyranny and show your support for the Russian people."
After being taken off stage by security staff, Tatchell explained he never intended to disrupt the concert; rather, he wanted to make a short, symbolic statement.
"Gergiev is a great conductor but he colludes with a tyrant and shows little concern for freedom and equality," he said. "I may have annoyed some concert-goers but others seemed supportive. It was all over in two minutes. Gergiev’s performance was only briefly delayed."
A Barbican spokesperson said: "We believe in the right to free speech and people are permitted to protest and make their views known. However, alongside the LSO, we respectfully ask that these protests happen outside the concert hall and anyone disrupting concerts will be asked to leave for the benefit of other audience members.
"The Barbican actively promotes and celebrates diversity in all our work; from our world class arts and learning programme that serves an increasingly wide audience to our commitment to maintaining a diverse workforce and promoting a robust equal opportunities policy that ensures equality and fairness in the treatment of all our employees."
The LSO said they hoped for a quieter evening at their concert on Friday night, where they performed Berlioz's viola concerto, Harold in Italy.