A thin line separates labours of love from vanity projects. Where does Barry Gibb’s Greenfields: The Gibb Brothers’ Songbook Vol. 1 lie? Its portentous title points to a labour of self-love from the last remaining Bee Gee. But the album, which pairs him with country and Americana singers in reinterpretations of Bee Gees songs, turns out to be a worthwhile addition to a heavyweight discography.

According to the record books, Gibb is pop’s second most successful songwriter after Paul McCartney. He and his brothers Maurice and Robin are frozen in popular memory as mid-1970s disco kings, a toothy trio of beaming men in open-chested white shirts singing “Stayin’ Alive”. But that does scant justice to the breadth of their songcraft.

Early Bee Gees records from the 1960s were cut from The Beatles’ psychedelic cloth. But they could also turn their hands to West Coast harmonising, orchestral pop and melodramatic ballads. The switch to disco followed a 1975 move to Miami. Versatile but not generic, they had an emigrant’s adaptability to different environments. The habit was instilled in childhood: their family was among the “Ten Pound Poms” who moved from the UK to Australia in the 1950s. (Kylie Minogue’s mother was on the same boat.)

Barry is alone now, following the deaths of Maurice in 2003 and Robin in 2012. Recorded in Nashville, Greenfields fulfils a longstanding ambition. In 1970 he made a country-flavoured solo album, The Kid’s No Good, which was junked when he returned to the Bee Gees’ fold. “I love country music and I probably allowed a little more than I should have to influence me,” he said of the unreleased project.

That love is given full rein on Greenfields, aided by a starry cast of guests. “I’ve Gotta Get a Message to You”, with Keith Urban, is given a Stonesy honky-tonk swagger. “Run to Me” is glitzed up into a big duet with Brandi Carlile. Dolly Parton, whose 1983 hit with Kenny Rogers, “Islands in the Stream”, was written and produced by Gibb, joins forces with him for “Words”. Sweeping orchestrations and steel guitar give it the sophisticated feel of the so-called “Nashville sound” from the late 1950s.

At 74, Gibb leaves much of the vocal heavy lifting to his companions. The former maestro of the falsetto sounds particularly earthbound next to Alison Krauss’s soaring, pure tones on “Too Much Heaven”. But the indelible melodic identity that he imprinted on the Bee Gees’ work comes across handsomely in the new arrangements: Saturday Night Fever’s “Jive Talkin’ ” shimmies from disco dance floor to Music City bar without missing a beat.

★★★★☆

‘Greenfields: The Gibb Brothers Songbook Vol. 1’ is released by EMI