British folk-rock act Mumford & Sons is celebrating its double Grammy nod. The band has recently returned from a tour in the U.S. where it has moved 428,000 copies of its debut "Sigh No More" according to Nielsen SoundScan.

The band is up for best new artist (up against fellow U.K. act Florence and the Machine, Justin Bieber, Esperanza Spalding and Drake) and for best rock song for "Little Lion Man."

Artist manager Adam Tudhope, joint managing director of Everybody's in London, tells Billboard.biz, "They are obviously delighted, they are over the moon."

The band was developed by the management and recorded its debut with producer Markus Dravs in London. International licensees came on board during the recording. (Island/Universal licensed the album from the band's Gentleman of the Road label and released it in the U.K. in October 2009.)

Tudhope believes their live reputation and extensive touring in the U.S. is a big part of their stateside success. He also credits the work by U.S. label Glassnote, which released the album in February 2010, and says CEO/founder Daniel Glass and his team has been "extremely dedicated - above and beyond the call of duty."

"Daniel Glass flew to Arkansas to persuade Walmart to take the album even though it had swearing on it," he says.

"It's nice to be part of that family [Glassnote]," says Tudhope, who adds that the album has "definitely exceeded expectations" in the U.S. "It's pretty extraordinary."

The first U.S. radio single "Little Lion Man" peaked at No. 1 on Billboard's Alternative Songs chart in October and "The Cave" is currently at No. 22 on Alternative Songs.

The Grammy nominations have not changed Mumford & Sons' campaign schedule - the plan for 2011 was always to focus on the U.S.

"We feel we are only halfway through the campaign [in the U.S.]," he adds. "Next year is all about America and making a new album."

Tudhope says the band is plotting large theater shows (5,000-plus capacity) in the U.S. in April, followed by festivals and further touring in late summer. As for a Grammys performance, Tudhope says they haven't been asked so far.

British Grammy Nominees

Other British nominees for the Grammys include Muse, which has three nominations: best rock album for "Resistance" (Warner Bros) and best rock performance by a duo or group with vocals and best rock song for the title track. Sade's "Babyfather" (Epic) is up for best pop performance by a duo or group with vocals and "Soldier of Love" is up for best R&B performance by a duo or group with vocals.

Scottish singer Susan Boyle's Syco debut "I Dreamed a Dream" is up against albums from Katy Perry, Justin Bieber, Lady Gaga and John Mayer in the pop vocal album category. "Up against wonderful artists like Lady Gaga and Katy Perry - I didn't expect this for a moment but how fantastic just to be recognized like this with a nomination on my first album," Boyle said in a statement.

La Roux and Goldfrapp are both nominated for best dance recording and electronic/dance album (the latter is dominated by U.K, acts with Groove Armada and Chemical Brothers also nominated). Goldfrapp is nominated for its track "Rocket" and the album "Head First" (Mute/EMI); La Roux for its single "In For the Kill" and album "La Roux" (Cherrytree/Interscope).

The most nominated British artist was guitarist Jeff Beck. He is up for a total of five awards for his album "Emotion & Commotion" (Rhino) and for his collaboration with Herbie Hancock, "Imagine."