IN HIS travels from Glasgow to Jamaica, and to hell and back, John Martyn must have called countless pubs his local - but surely there can have been few more homely than Carroll's. If you were a cynic you might say that Thomastown in County Kilkenny had a touch of the Brigadoons, or the Irish equivalent, about it. But that is a cynicism born of watching too many episodes of Ballykissangel on TV and seeing too many Oirish bars with names such as Shamus O'Bogtrotters taking over your local high street.
In Thomastown, time genuinely seems to have stood still; the shop signs look old because they are. And in Carroll's, a poster on the wood-panelled wall of the snug confirms that back in 1983, the 6th Lisdoonvarna Festival featured Martyn alongside Van Morrison, Rory Gallagher and - where are they now? - Amazulu.
I am wondering if Martyn remembers the gig amid the endless touring and partying, the bankruptcy and the bevvying, the drugs and the divorces, when the veteran folkie shuffles into the boozer. A big bear of a man, he attracts the attention of the barmaid with a cry of "Nurse!" He orders a cider and a double vodka, pours the latter into his pint, and downs half the concoction in one go.
"It's been a bad leg day," he says in a grizzly Glaswegian accent, and slumps onto the bench beside me.
Last spring, almost a year to the day, Martyn had his right leg amputated below the knee. Until recently he was in a wheelchair and he is still getting used to his prosthetic limb. Another poster behind the bar is collecting names for a bus trip to a forthcoming Martyn gig in the next town, part of his comeback tour. He wants to perform standing up but fears he may have to stay seated. It was all that standing on stage, he reckons, that did for the leg. Well, that and his fondness for ending up flat on his back, post-gig. From a background in folk music, he enjoyed - and that is very much the right word - a rococo lifestyle that would put most self-styled wild'n'dangerous rock stars to shame.
Martyn is with his girlfriend Theresa today and this is a near-permanent state of affairs now. "Mine's is a typical Irish story," he says. "I fell in love with a colleen five-and-a-half years ago, and I've been here ever since."
While Theresa chats to the staff, and the nurses keep the drinks coming, Martyn talks, for the first time, about his illness and his determination to get back on the road and resume his career at the age of 55. Once a troubadour, always one. It's a tale of courage, told with humour and coloured with hippy logic.
"I developed a cyst on the back of my knee. Big as a cricket ball, although it was there for seven or eight years without me knowing. The doc told me it was a baker's cyst, caused by a build-up of synovial fluid, which is the gluey gear between the patella and the rest of the knee."
"I'd produced too much of it and I guess that was from me putting all my weight on it with my f*****g great big Les Paul guitar."
"Thinking back, there were lots of times when I fell off the stage. I remember getting booed in Cambridge because the crowd thought I was drunk. It was this motherf****r that let me down, and it vindicates me for those seven or eight years. All the other nights I fell over was down to pure and shameless over-indulgence."
"Anyway, one day I got a jolt from an amp. I've had a few of these shocks in my time and normally I'm quick to recover from them - but six hours later I didn't feel at all cool. The cyst had popped. The leg was infected and the nerves were shot. One toe went in one direction, the one next to it in another, and my heel started climbing up my ankle. Man, it was painful, I couldn't walk."
Was there an alternative to amputation? "Death, probably," he says with a chuckle, before lifting up his trouser leg to show me the false limb. "In situations like that, you've just got to trust medical opinion."
Martyn has lived with the prosthetic for three-and-a-half months - he's still trying to think of a name for it - and reckons it's going to need a lot of breaking in. "See these chops?" he says, displaying the heavily calloused fingers of a lifetime's strumming. "I've got to get the end of my leg that hard. It's got to be so f*****g strong I can stub out a cigarette on it and not feel a thing."
The illness and its aftermath put Martyn off the road. "I was two years in bed or in my wheelchair," he says. "I'm so glad I met Theresa because when I got ill things got very sticky for me. I don't own any property now. Bit by bit, I had to sell it all off. There was a cottage in Lanarkshire, a right lonely place which was hard to heat, and that's gone, too."
Martyn did not want to record a new album while recovering from the operation, but the 21st album of his long career eventually became a financial necessity.
"I had no source of income," he admits. He's not very happy with On the Cobbles, which had to be finished with the help of painkillers, and reckons the sound is "too clean". Maybe it will grow on him. He's certainly proud of 'My Creator', describing it as "kind of like a Buddist-Baptist hymn", but says the song will never be finished. It's destined to be a work-in-progress for as long as he's got the breath left to sing.
Just then, a silver-haired man with dancing eyes enters the pub and he and Martyn are soon engrossed in conversation about one of his other big loves, fishing. The man is a major landowner around these parts and has the rights to the River Nore, a favourite of Martyn's, who wants to get back on the banks as soon as his leg is up to it. Eventually, the pair agree to talk salmon later.
"I'll come round tonight, shall I?" says the landowner. "Tell me, what do you drink?"
"What doesn't he drink?" says Theresa.
Martyn apologises for the interruption and asks what he was talking about. "Booze, was it? Aye well, sometimes I get angry about what's happened to me, but anything I had coming was well on its way. I've hammered my body all my life. If I wasn't playing rugby I was rock-climbing or deep-sea diving or fighting."
"Then I was flying round the world, doing drugs, staying out too late and drinking far too much. But anger is cool, you know, because I've always thrived on being aggressive and I can channel it into a positive vibe. The angrier I get, the hipper and sweeter I seem to become."
What a hip, sweet, angry life John Martyn has had. His parents split up when he was young and summers were spent in Surrey with his English mum - on her houseboat, which was "a gas" - but for the most part his upbringing with his Scottish dad was thoroughly Glaswegian.
"We lived in the South Side, which in the 1950s was quite posh," he says. "Four floors up in a tenement, everyone knew each other. There was the Russian couple, Mr and Mrs Young, both mad commies; the Levinsons, a Jewish brother and sister; the Winchester sisters, nice old dears who never married. And up on the top deck, the bad yins like us."
Martyn can never walk, hobble or fall off a stage without playing his most-loved song, 'May You Never', which contains the line: "May you never lose your temper if you get hit in a bar-room fight/ May you never lose your woman overnight."
It was his Scottish granny who introduced him to drink, aged 12, when she would wake him for his 4am milk-round with a dram of whisky.
Down the years, good friends have become casualties of showbusiness, including the Free guitarist Paul Kossoff and fellow singer-songwriter Nick Drake. Martyn wrote the title track of 1973's classic Solid Air album about Drake, in an attempt to pull him back from the abyss, but the following year he killed himself. When Drake's name comes up today, Martyn closes his eyes. "He was my friend but I can't talk about him any more because everyone does it now. It's ghoulish."
He summons Theresa, asks her to take him home, and we bump along the country lanes to her white-walled cottage, where the first thing he does is plug in his Les Paul.
In the cluttered front room stuffed with African art, he plays along to a backing track while sitting down. He shuts his eyes again and is soon lost in the reverie. When Theresa hands him a big spliff I start to wonder if I'll ever get him back, but then he says: "Now, what were we talking about - fishing, was it?" Strangely, he's now speaking in an English accent.
I ask him about other fellow travellers; he used to carry folkie Hamish Imlach's guitar in exchange for lessons. "Clive's Incredible Folk Club in Sauchiehall Street - run by Clive Palmer, who went on to form the Incredible String Band - didn't open until 2am and was very bohemian."
He was discovered by Theo Johnston, "a little, fat, mad hustler of the finest kind, who brought a countess back from Poland on his scooter and married her". His debut album, London Conversation, took him two-and-a-half hours to record in a Putney bedroom for the cost of £ 124 and was released in 1967.
But he eventually tired of the folk scene. "It was the same guys, all playing C, F and G. If you didn't wear corduroys, stick a finger in your ear and stand on one leg - that would be easy now - you weren't one of them."
He started to experiment with sound, arming his guitar with fuzzbox, echoplex and phase-shift. "I had everything and the kitchen sink on there," he says.
Martyn's tours with Pentangle's Danny Thompson were sojourns to the edge of darkness. After one unholy session, he woke up to find that Thompson had nailed him under the hotel carpet. And the sonic questing continued in partnership with dub-meister Lee "Scratch" Perry, the pair recording 1977's One World album in the midst of the punk revolution.
He tells a story about their time spent hanging out in Jamaica but loses me after the bit about the CIA, the boiled sheep's head, the stolen silver dollars and his discovery of Perry taped to a tree. He was chanting: "Tree, I love ya man. De fig, de leaf..." Perry's philosophy for life is that if you act like you're mad, you keep the real maddos at bay, and it's one Martyn has often borrowed. So does he hug trees, too? "No, round here they hug me."
A more recent collaboration, with Sister Bliss of the dance act Faithless in 2001, brought him his first chart single with 'Deliver Me', an event The Scotsman deemed worthy of celebration in its leader column.
He was the first white artist to sign with Island Records, and the coolest label in rock at that time was "a sweet place to be". He missed supremo Chris Blackwell's influence later in his career but he's not one to harbour regrets.
"My excesses weren't like lollipops handed over at the school gates," he says, his voice now back in Glasgow. "I knew what I was doing with those drugs, man, and I went for it. Heroin and the rest, I loved every single piece of mince I took. It was great feeling waking up in the morning and thinking, 'Well, I tried that and I'm still alive.' But I know I'm a lucky bastard."
"I'm very lucky to have met Theresa. I used to be hopeless with women - I fell in love too easy or not at all. If your own family unit is bust, you can end up doubting love, and I made mistakes with both my marriages."
"Theresa is the only woman I've wanted to marry, and the only one I've asked. She's turned me down twice and now I'm such a fat git after what's happened to my leg that I've broke her sofa."
"I've put on three-and-a-half stone because I haven't been able to go swimming. Basically, I go round in circles now. But I'm going to get a pair of flippers and lose some weight. Then maybe I'll ask her again..."
On the Cobbles is released on Independiente tomorrow. John Martyn plays the Glasgow Royal Concert Hall on May 10.