For much of the past year, Mumford and Sons have focused considerable effort into creating their fourth studio album. Amidst that flurry of creativity, the members of the folk quartet have also confronted some major crises, on personal and social levels, with real action. Marcus Mumford, who lives just minutes away from the Grenfell Towers apartments, immediately responded with hands-on, collaborated efforts of assistance to his neighbors following the fire tragedy. The musician immediately established football programs for youth as an emotional outreach and form of competent childcare for families in need, and his stalwart support for the community continues in light of what he called a “shambolic” governmental response.

The very human disaster at the Grenfell Towers is only one example of something that deeply touched Mumford and Sons on a personal level and simultaneously connected them more deeply with each other and their multitudes of fans. Their fans continually seek the messages, of hope through darkness, in the songs that echo through the foursome’s anthems. E-mail messages went out to fans on Thursday, September 20, announcing that “The Delta era has started,” heralding the name of the fourth collection from the band, and giving an offering of the first lyric video for “Guiding Light” featuring a gathering of fans.

In September 20 features with the BBC and Billboard, Mumford and Sons elaborated on the maturity and musical directions encompassed on “Delta,” and why the process of personal and artistic evolution keeps them grateful.

First responders

Mumford and Sons have never been too prescient about preserving their music, and the band characteristically ascertains the value of a song by the response from fans. Marcus Mumford, Ben Lovett, Winston Marshall, and Ted Dwane turned up as surprise headliners at this year's Newport Folk Festival, and performed “Guiding Light,” “See a Sign,” and the ethereal “Woman” at Hungary’s Sziget Festival last month, each to rousing approval.

This song selection process for tracks worthy of being on “Delta” became decidedly brutal.

There were 45 songs in contention when Mumford and Sons came under the care of producer Paul Epworth, who has managed to make very memorable music with Adele, Rihanna, and Coldplay. The roster was sliced first to 24 and then took another pruning to the final listing.

Initially, the band playfully wrote FBCM (signifying “Full-Blown Crisis Mode”) on a whiteboard as they convened over song choices, but at their interview time, they were casual and comfortable, sharing tea brewed by bassist Dwane.

Not speeding to find the best

“What we needed was a good album, not a fast album,” insists Marcus Mumford, defending the more than three years between this collection and 2015’s “Wilder Mind.” Winston Marshall jokes that care is important in creating a lasting record, because “once it's out, it's out forever unless you’re Kanye West.”

The talents of Winston Marshall on banjo are reportedly on almost every track of “Delta,” but there are a few that may provoke fans to pause before recognizing the instrument, according to Mumford.

A cello banjo was played on “Woman,” and Marshall was challenged by pairing what he calls the “disco groove” underneath the chorus of “Guiding Light” with banjo, but the end result proved worth the effort.

“Some of our songs that have connected the most with people have been the hardest,” Marshall asserts.

Keyboardist Ben Lovett reflects that “death, depression, and divorce” are also challenges that have impacted the band through the process of making the album. He notes that this “major stuff” confronting the Mumford and Sons members inspired a sense of “grappling properly for the first time with manhood.”

There have been interludes of joy along the way, as Marcus Mumford and his wife. Carey Mulligan expanded their family, and Lovett ventured into the area of providing truly allergy-free cuisine with his restaurant partnership starting in July.

The musician has long had to provide his own food on world tours for fear of encountering peanuts or nuts in some form, of which even food preparers can be unaware.

The title “Delta” represents personal and professional significance for these folk-rock masters. They link the convergence of the River Delta with the ocean to moving from the relatively safe rivers of life to the unknown seas. Delta is the fourth letter in the Greek language, and this is the fourth album from Mumford and Sons. Lovett proposes that many bands are defined by fourth albums, he feels that “Delta” marks a defining point for this band. The album will release on November 16.