U2 brought London to a standstill tonight (February 27) after performing a surprise rooftop gig.  The Dublin four-piece attracted over 5,000 fans to Regent Street during rush hour as they capped off a hectic day of promotion for their 12th studio album 'No Line On The Horizon'. Rumours of the gig, which was staged on top of BBC Broadcasting House, had been posted on several message boards t More..hroughout the day. Thousands of fans turned up before the band eventually arrived at 6.45pm to perform a 20 minute set which included recent single 'Get On Your Boots' and new album track 'Magnificent'. They also delighted fans by blasting out their number one hit singles 'Beautiful Day' and 'Vertigo' which saw Bono segue into The Who’s 'Substitute' and The Beatles' 'She Loves You'. As the band launched into the latter, Bono told the crowd: "This is the first time this band has got to play our (new) songs for anyone so thanks for listening," before he joked: "I'm afraid of heights by the way. So why would you write a song called 'Vertigo'?" The impromptu gig echoed scenes of The Beatles' 1969 rooftop gig at Apple's London headquaters and U2's 'Where The Streets Have No Name' video which saw the band play on the rooftop of the Republic Liquor Store in LA in 1987 before they were shut down by police. This time though, police allowed them to play a full gig as they shut off Portland Place to divert traffic away from the area.