Elton John / Leon Russell, The Union (Mercury)

Elton John you may be familiar with, but the chances are Leon Russell has slipped your mind.

Russell was a significant journeyman of the 1960s and early '70s – Dr John confused with Father Christmas in a top hat in Tulsa, Oklahoma. He played piano for Phil Spector then turned himself into a celebrity sideman, famously conducting Joe Cocker's "Mad Dogs and Englishmen" jolly-up, and wrote hits of his own, many of them riding on a secular "Gospel" train. "A Song For You" might ring a bell. The other thing he did was influence Elton John.

Russell is currently not terribly well. But that didn't stop him responding to his greatest fan's blandishments and heading into the studio with Sir Elt, the producer T-Bone Burnett, a gaggle of Gospelly ladies, Tom Waits' guitarist Marc Ribot and – doof! – the great session drummer Jim Keltner, who was still wearing the sweat from making Jerry Lee Lewis sound like The Killer again. What emerges is one of the pleasantest surprises of this or any recent year.

It's not all Gospel by any means, but that sound – those rolling-hill chord structures, the weight of two pianos, that electrical charge in the chest – it governs The Union. The music is dark, resonant, sepulchral at times, if any piece of work so fundamentally secular in nature can be sepulchral. It's as if, having stuck their fingers in the genre socket, the old boys can't let go of the buzz.

The writing credits are shared, collegiately, between the headliners and Bernie Taupin in various permutations but, for all the diversity of musical allusion, what underpins the material is hymnody: hymns to fate, to love's passing, to facing down old age, to American history (Neil Young turns up to do a Civil War bleat on "Gone to Shiloh"), to American music as a generality. "Jimmie Rodgers' Dream" is a country-ish chuffer while the filthy oil lubricating the 32-bar blues, "Monkey Suit", might have leaked from the sessions for Exile on Main St. Only "Eight Hundred Dollar Shoes" really suffers from that old Taupin weakness for packing too many trite metaphors into too tight a space – and even then the song is almost redeemed by a "Candle in the Wind" of a tune.

And while Russell sounds as frail of throat as any man is entitled to sound after five hours recently spent under the surgeon's knife, Elton John has never sounded more soulful or committed. He doesn't exactly carry Brother Leon but he surely provides all the virile support a frail fellow could possibly wish for.

In the end it's left to one of the more obviously knocked-off, back-of-a-fag-packet songs, "There's No Tomorrow", to reveal what underlies the whole project. It's a minor-key hymn to the importance of getting it on in the moment and it unwinds like a Spiritual: block-chording piano, the Gospel ladies singing with penitent savagery, a beautiful Ribot solo, then the dying fall of Russell's last cadence. Not subtle, but serious as your life. It's a really good record.