British indie rockers alt-J are still surprised at how successful they have been since their debut album won the Mercury Prize, the band’s Gus Unger-Hamilton has said.

The group, who have been confirmed as headliners at Latitude Festival this year along with Solange Knowles and The Killers, are also thinking about their fourth album, despite having only released their third last year.

Alt-J’s debut album An Awesome Wave won the Mercury Prize in 2012 and was also the BBC Radio 6 Music album of the year.

The Leeds-based band, who have scored success across the globe, were nominated for a Mercury Prize again for third album Relaxer last year, and they have been nominated for other top industry prizes including Brit Awards and a Grammy.

The band’s keyboardist Unger-Hamilton said the positive reaction from fans and critics is still a shock sometimes.

“It still kind of blows my mind that things have gone so well for the band,” he told the Press Association.

“Every time we put out a new album, you get this kind of slight fear thinking, ‘Oh man, this is going to be one where they all go, nah – we’re not interested anymore.’

“But so far, touch wood, it hasn’t happened, so we’re very lucky and we’re looking forward to seeing how things go in the future.”

He said, of the pressure of having to keep up appearances: “We don’t take it for granted that the success level is where it is.

“And we would love it to stay where it is, absolutely. But I think, broadly speaking, we feel that, in terms of the music we make, we feel quite free from pressure.

“We’ve never really promised our fans to be one kind of band, we’ve always been known for being quite erratic in our songwriting and writing all kinds of different songs and sounds, blending genres, so in that sense we feel quite a sense of liberty in what we do creatively.

Barclaycard Mercury Music Prize 2012 - London
From left to right, Joe Newman, Thom Sonny Green, Gus Unger-Hamilton and former member Gwil Sainsbury of alt-J after they were announced as winners of the Mercury Prize in 2012 (Yui Mok/PA)

“But, absolutely, we do hold ourselves to a high standard in terms of what we put out.”

Of returning to Latitude Festival for the fourth time and as headliners for a second, Unger-Hamilton said: “We’re really excited, it’s a festival we really feel that we fit in very well at, we really feel at home there.

“We’ve really risen through its ranks, going through the Lake Stage to the BBC Radio 6 Music Stage to the main stage, we’re so happy to be going back.”

Unger-Hamilton, who appears in the alternative rock band alongside lead singer and guitarist Joe Newman and drummer Thom Sonny Green, said there are “thoughts” between them for their fourth album.

But, he said, they are “not actively working on it” at present, as they have been focusing on their Relaxer tour since June last year.

“We definitely want to do a fourth album, and I think once we’ve got this tour out of the way and let the dust settle a bit, I’m sure we’ll be back in the studio and working on stuff for next year,” he said.

He said that he is getting married in spring next year, and is hoping to take some time away from work to focus on planning his nuptials.

2014 MTV Video Music Awards – Arrivals – California
Solange Knowles is also in the Latitude line-up (PA Archive/PA)

“But who knows,” he added. “We may decide we have so many great song ideas that we have to go straight into the studio!”

Alt-J will take to the Obelisk Arena at Latitude on Sunday July 15, the final night of the festival.

Other performers in the line-up include Rag’n’Bone Man, Mogwai, Wolf Alice, The Vaccines, Jessie Ware, The Charlatans, James and Benjamin Clementine.

The festival, which is now in its 13th year, includes non-music acts such as comedian Harry Hill, while Recirquel Contemporary Circus: Paris de Nuit will add a theatrical touch to proceedings.

Latitude Festival takes place from July 12 to July 15 at Henham Park, Suffolk.