John Martyn – the man and his music – is a glorious mess of contradictions. His loggerhead consciousness, rooted in the early separation of his mother and father, has provided the emotional fuel driving a four-decade journey in the company of dancing angels and bellicose demons. On the broad stage of Martyn’s psyche, one feels, the dockyard ruffian is constantly wrestling with the sainted minstrel, the romantic idealist dodging the drunkard’s blade.

These many internal conflicts are clearly on show throughout this career-spanning four CD set. Compiler John Hillarby runs a compendious JM website, and his intention to include at least one track from each of Martyn’s 22 studio albums since 1967 initially sounds like needless bookkeeping, especially given the maestro’s dispiriting run of overproduced records in the 80s and the wilderness years of the early 90s. But far from fulfilling the usual function of a compilation as an introduction to an artist’s work, Ain’t No Saint is more like a re-hanging, with Martyn’s permanent collection re-viewed through a fresh curator’s eye. Hillarby’s selection acts as a contrast filter, fading down the more familiar aspects of Martyn’s work and bringing his exploratory tendencies into sharper focus.

Like 2006’s Pentangle box set The Time Has Come, the backbone of these four discs is a healthy proportion of previously unreleased material, studio outtakes, and alternative versions. You can locate Martyn’s songs in time just by the grain of his voice. The pastoral pipedreams of late 60s teenage compositions “Fairy Tale Lullaby”, “Sing A Song Of Summer” and “Tree Green” are hummed with an audible grin; by 1972, touring, alcohol and other performance enhancers have rubbed a fine emery board over his sylvan set of pipes. As his marriage to Beverley cracks under the strain, demons seize possession of his larynx, causing the vexed roar of “Dealer” and “John Wayne”. On songs like “Couldn’t Love You More” and the previously unissued “Working It Out”, where he’s beating himself up over his disintegrating marriage, he moans like a stricken centaur.

But – appropriately for the Briton who worked hardest to send electric jolts through a complacent folk circuit – every album contains startling polarities, channelling the alternating currents of erotic tenderness (“You curl around me like a fern in the spring”, from “Go Down Easy”) to macho swagger (“Big Muff”) to publicly-laundered apologies to his wife for absences and infidelities (the title track of this compilation is supplied here in a vocal-free version shaved of its desperate “get it together” mantra).

As one of the most important pilgrims walking away from the London folk scene of the late 60s, Martyn set course for deeper, freer waters than any of his contemporaries (Sandy Denny, Jackson C Frank, Ralph McTell, Al Stewart, et al). His epiphanic encounters with the electrically galvanised jazz of Pharoah Sanders, Weather Report and Miles Davis inspired the alternate early 1972 studio take of “Solid Air”, whose verses cede to a sparkling jewelled cave of improvised vibes, Danny Thompson’s slack double bass pools, and Martyn’s bastard’s brew of distorted wah-wah. A ten minute “Bless The Weather”, live in Edinburgh in 1973 (its “intellectual guitar” intro chippily disowned in a short audience preamble), phases in and out of rock and swing time and, over Thompson’s bowed drones, dips a toe into Indian raga modes.

The seven live tracks picked from the notorious UK tour of winter 1975 with longtime running mate Danny Thompson and improv drummer John Stevens (including three unused from the date that made up the original Live At Leeds release) emphasise Martyn’s tender, confessional side. Another “Solid Air”, from March 1975 at London’s Rainbow, gains extra poignancy less than four months after the death of its dedicatee, Nick Drake; while loose and abrasive jams on “Rather Be The Devil” and “Outside In” ignite the group’s nitro-glycerine virtuosity.

One World is represented here by full-band live takes of “Big Muff”, “One Day Without You”, a sketch for Ambient guitar odyssey “Small Hours” (originally titled “Space Peace”), and a more contemporary interpretation of “One World” itself, where the original’s aching alienation cleaves closer to its purportedly socialist concerns. That year, 1977, he was kicked out by Beverley and physically attacked by Sid Vicious (even though parts of One World are every bit as nihilistic as Never Mind The Bollocks), precipitating his momentum from the idylls of his early music to the monster-populated id of 1981’s “Grace And Danger”. Like Dylan after his motorbike smash, the timbre of Martyn’s voice changed irrevocably from here on, as did the texture of his arrangements under producer Phil Collins, which appeared to be Martyn’s last-ditch leap at the kind of global penetration the ex-Genesis man achieved.

Instead, Martyn’s career floundered. “Ain’t No Saint”’s only significant dip in quality comes with the second half of disc four. During a breathless rush through Martyn’s mid-80s and 90s via Montreux and Jools Holland TV appearances, keyboard presets, fretless basses and AOR saxes languish at dullard tempos, the singer strains for notes and his guitar is mixed too low.

Instead of attempting to honour this fallow period, it would have been refreshing if Hillarby had reached out beyond the solo canon to include some of Martyn’s extracurricular appearances with the likes of Claire Hamill, Paul Kossoff, Burning Spear, John Stevens’s Dance Orchestra and on Neil Ardley’s 1979 jazz/New Age symphony, Harmony Of The Spheres, to give a wider picture of Martyn’s versatility.

Reassuringly, “Over The Hill”, from this year’s BBC Folk Awards, shows a post-amputation Martyn regaining the liquid fluency of his best years, with an endearingly teddyish drawl. Ultimately, the minstrel has seen off the ruffian.

ROB YOUNG