It was the film O Brother Where Art Thou that started British band Mumford & Sons on the course that would make it internationally successful.

The four guys, who first got together in a Putney rehearsal studio under the railway tracks five years ago, are ready to release their second album, Babel, a followup to 2010’s Sigh No More.

It’s a different kind of record with more of a rock sound that reflects the life on the road they’re leading since they appeared on the Grammy Awards in 2011.

"It was just how we were writing songs this time around. It was a bit of energy from the gigs," said Marcus Mumford in an interview with CBC’s Q cultural affairs show. "It came out of a charged few years."

Mumford described the folk-bluegrass influence that gave them their start.

"We gravitated in the sense that that was what we were listening to when we started the band. We’d come from a whole range of musical backgrounds – then we got introduced really to bluegrass and Americana, acoustic Americana honestly through O Brother Where Art Thou," he said. "That movie kind of heralded the advent of bluegrass in mainstream British culture," 

Adopting that format required everyone to change their style and their instruments. – Mumford, formerly a drummer, took up acoustic guitar, Country Winston Marshall learned banjo, Ted Dwane moved onto upright bass and Ben Lovett adapted his piano sound.

Mumford & Sons have taken on a heavy touring schedule ever since, committed to playing smaller festivals and smaller towns, so they could indulge their taste for travel and get close to fans.

They’ve also made some high-profile appearances – sharing a stage with Bruce Springsteen and Neil Young and that Grammy gig with Bob Dylan and the Avett Brothers.

"There are a lot of gigs around a handful of incredible moments like that," Mumford says. "We keep our heads down and work the road, that’s all it is. There is a strange feeling of accomplishment that comes with that."

They’ve heeded the advice to take to social media, but prefer putting Lovett’s photos up on their website or running their online book club to taking up Twitter.

"We’re making an effort to engage with people who listen to our music without the direct social media thing that is recommended. We felt like it wasn’t for us," Mumford says, adding "we can only give so much of ourselves away,"

"There’s enough in the songs, the songs leave enough on the table already, without having to unpack them for people and we give away a lot of ourselves at live gigs," he said. All four are songwriters and songs are often a collaborative effort, with one contributing a few lines or a musical riff and the others building on it.

It’s been nearly three years since they were last in the studio and Lovett told Q he was "happy" to finally have a second recording to offer fans.

The rock vibe in Babel is intentional, he said. Mumford and Sons played two songs during their visit to Q.

Babel will be released Sept. 25.