New Horizons

U2 have released their 13th album. Photo / Supplied

If Bono is afraid of heights – as he claims before launching into the appropriately titled Vertigo – then the last place the U2 frontman would want to be is on the roof of BBC Broadcasting House in central London. But that was where he and his bandmates were at the end of a long day last month promoting their new album No Line on the Horizon.

The evening marked the second occasion that the Irish quartet had played tracks from their 13th opus after performing before a small invited audience. With concertgoers usually viewing the larger-than-life rockers either as tiny specks on a distant stage or towering over them on gigantic video screens, it would have been a disconcerting experience to stare into the whites of Bono's eyes (in the few moments, that was, when he actually removed his ever-present shades).

The so-called "biggest band in the world" were in their element as they played their new material "for the first time to anyone".

However, they proved even less visible than at one of their stadium shows: from the crowded street below, the only time that I caught a glimpse of Bono was when he leaned over the railings to sing a few lines.

Guitarist The Edge, bassist Adam Clayton and drummer Larry Mullen appeared to wave goodbye before finishing with Beautiful Day, the last of their four-song, 20-minute set. First up was the album's glammy, T-Rex-esque lead single Get Your Boots On, followed by heartfelt power ballad Magnificent.

Next was old favourite Vertigo, which had most of Regent St singing along even if it didn't please the band's harshest critics, who pointed out that rooftop gigs were nothing new. Most famously the Beatles played atop their label headquarters in nearby Savile Row in 1969, while U2 filmed the video for 1987's Where The Streets Have No Name during an impromptu show on a roof in Los Angeles before being shut down.

But now it was a more official affair with Bono even thanking the Metropolitan Police, who closed the surrounding roads, "for sorting this one out for us".

It has been a long time since U2 reinvented themselves after the excesses of 1988's Rattle and Hum by embracing dance music and cutting edge technology on 1991's Achtung Baby. It precipitated the Zoo TV live extravaganza, which featured spectacular visuals and Bono phoning the likes of President Bush and Salmon Rushdie from stage each night. Their two albums to date this decade, 2000's Leave Them All Behind and 2004's How To Dismantle an Atomic Bomb, have been more traditional affairs that harked back to their classic 80s sound.

Despite talk of experimentation and a return to the improvisational working methods of Achtung Baby, No Line on the Horizon very much follows in its predecessors' footsteps. The jangly guitar riffs and delicate textures of tracks such as Magnificent and the gospel-tinged Moment of Surrender bring to mind Unforgettable Fire.

That 1984 album was the first time the old schoolfriends teamed up with producers Brian Eno and Daniel Lanois, who have since worked on another six U2 albums, including this latest. Suffolk-born Eno has produced work for punk pioneers such as Talking Heads and Devo. He honed the mainstream-friendly signature on Unforgettable Fire that has become ubiquitous since he helmed albums such as Coldplay's Viva La Vida and Dido's Safe Trip Home.

After initially attempting to work with Rick Rubin, best known for collaborating with the Beastie Boys and the Red Hot Chili Peppers, U2 turned not only to Eno and Lanois but also Steve Lillywhite, who produced the band's first three albums.

They decamped to Fez, an ancient city in Morocco which, according to Bono, is the North African state's "holy seat, its religious capital". Claims The Edge: "We got so many great ideas out of that time that it was clear that we were going to make a record." But U2 haven't emulated New York indie band Vampire Weekend, who last year mixed African rhythms with rock refrains on their debut album. The only track on which such influences emerge is on the opening beats of the freewheeling Fez: Being Born.

Despite fears that U2 were struggling to finish the album when its release was postponed from November to this month, No Line on the Horizon is a solid cohesive effort. But with downloading and the recession taking their toll on the beleaguered recording industry, much is riding on No Line on the Horizon, which should be one of the bestselling albums of the year.

If the 5000-strong crowd that witnessed the supposedly secret gig is any indication, then U2 and their record company should have nothing to fear. But Get Your Boots On only entered the British charts at number 12, the lowest placing in more than a decade, and the band are not taking anything for granted. "It's hard to tell if we're going to have success," Bono told the BBC's Culture Show.

"I do not think it is a given. People have 12 albums; maybe they don't need a 13th. It would have to be very special for people to do that and we think we've come up with something very special. Unfortunately, that is not in our control."

* No Line On The Horizon is in stores now.