Biffy Clyro will play a surprise show at 8pm [BST] tonight (June 12) at London's Tate Modern gallery. The band tweeted news of their performance, which is in support of Agit8, raising poverty awareness ahead of next week's G8 Summit in Northern Ireland. Mumford and Sons recently teamed up with Elvis Costello for a cover of Bruce Springsteen's 'The Ghost Of Tom Joad' for Agit8, an "urgent call to action against extreme poverty" launched by Bono's One Campaign. Springsteen's original 'The Ghost Of Tom Joad' is a folky protest song named after a character from John Steinbeck's The Grapes Of Wrath. It served as the title track for The Boss's 11th studio album, which came out in 1995. Scroll down to watch the Mumford & Sons and Costello version, which slips in a few bars from 'Do Re Mi', a classic American folk song by Woody Guthrie. "We wouldn't know what to say, so it's quite helpful to have music that says things for you," Marcus Mumford said. Other artists who've covered classic protest songs for the Agit8 initiative include, Ed Sheeran, Sting, Macklemore & Ryan Lewis and Kid Rock. More information and videos of all the songs can be found at