Rock band Biffy Clyro surprised fans when they sang FOLDING STARS a song they had vowed never to play live, at a London gig.
The Scottish rockers made a "snap decision" to include the number in their finale, according to NME.
Dressed sharply in black suits, the band played host to a range of guets at their Brixton Academy show.
MIKE VENNART sang on several tracks, while a full string section made a special appearance.
Fans were entertained by both recent and old hits including PUZZLE, 9/15THS and LIVING IS A PROBLEM BECAUSE EVERYTHING DIES.
On Friday, BIFFY CLYRO will be performing alongside We Are Scientists on the fourth evening of Mencap's Little Noise Sessions.
The concert will be held at Islington Union Chapel and will raise money for the learning disability charity.
Other bands taking part in the series of eight concerts include: KATE NASH, The Kooks, Snow Patrol and Keane.