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Buchanan, who was born in Leith in 1945, made history when he became undisputed world lightweight champion in 1971.
The only living British fighter in the International Boxing Hall of Fame, following his retirement he suffered from alcoholism and, recently diagnosed with dementia, he now receives round the clock care.
In "Undisputed: The Life and Times of Ken Buchanan", to be shown on BBC Scotland on Tuesday, the 76 year old ring legend studies old photographs from his life and career.
He recalls proud moments, from teaching playground bullies a lesson to the "magic" of representing Scotland, as well as the great tragedies of his life including the death of his most passionate supporter, his mother Cathy at the age of just 51, and the sickening low blow from ring legend Roberto Duran that cost him his world title.
He said: "I've had my life and I've had a good kick of the ball, and I've no axes to grind, none whatsoever. I've just lived my life and that's it because if I were to sit and worry about it I would never get any sleep.
"I'm just Kenny Buchanan, I was a world champion but that's all behind me, finished and done with."
He adds: "I think I'm a Jock Tamson, I don't put myself above nobody. Everybody is on the same level as me and I'm not feeling bad about my life and how it's went. I've had a good life -- I've had a great life -- I've done things that nobody in this country has done and I enjoyed it."
Buchanan took up boxing at eight years old, after persuading his dad Tommy to take him to Edinburgh's Sparta Club, and won his first medal aged eight and a half and weighing 3st 2lb. He made his international debut aged 17 and turned pro' after winning the British amateur title two years later in 1965.
He said: "I got bullied a wee bit at school because I was skinny. I had a wee bit of a chip on my shoulder but only because guys wanted to fight me, and then his brother would want to fight me because I would knock him out.
"It was just a left jab I gave him, and that was it. All I wanted to be was the champion of the world -- the best fighter in the world."
His dream came true on September 26, 1970 when he became WBA World Lightweight Champion after defeating Panamanian Ismael Laguna over 15 rounds in sweltering Puerto Rico.
He recalls: "It was roasting, absolutely roasting. I don't know (how I managed to survive that fight). I went out there two weeks before the fight. It should have been two months."
The same year, he was named the American Boxing Writers’ Association’s "Fighter of the Year", ahead of heavyweights Joe Frazier and Muhammad Ali.
In February 1971 he defeated Mexican Ruben Navarro in Los Angeles to add the WBC Belt and become the undisputed lightweight champion of the world.
Buchanan received the 1971 British Sports Writers' Sportsman of the Year Award, ahead of fellow Scotsman, Formula One champion Jackie Stewart.
He lost his world title controversially to Duran in June 1972. The fight at New York's Madison Square Garden ended after Buchanan was floored by a low blow at the end of the 13th round.
Looking at images of the punch that should have seen the Panamanian disqualified, Buchanan says: "You can see it a mile away, he's done it up the way."
Buchanan retired in 1976 following an eye injury but returned to the ring in 1978, finishing his career in 1982 with a record of 61 wins and eight losses.
The former world champion found it difficult to adjust to life outside the ring, however, and prior to developing dementia, struggled with alcohol addiction.
Speaking in the hour long documentary, his son Mark, 50, says: "We used to have arguments over it when we were younger and he said, 'Son, all I wanted to be was a world champion -- I wanted to be the best in the world at boxing'. He said 'I achieved that and I missed out on all my life, so all I'm going to do now is have fun and do what I want to do.
"He took it a little bit too much to the extreme in some cases, but he'd done what he wanted to achieve and nothing else mattered."
Mark adds: "He wasn't interested in the money or the fame really -- he wanted to be the best boxer in the world."Buchanan defeated Ismael Laguna over a gruelling 15 rounds in Puerto Rico in 1970 to become world lightweight champion - the first time in more than 50 years that a British fighter won a world title overseas.
He fought in temperatures up to 40 degrees in the stadium in San Juan and had to borrow an umbrella to protect him from the full glare of the sun between rounds.
And he dedicated the historic victory to his mother, Cathy, who had been his greatest supporter but died in 1968 from a sudden heart attack, aged just 51.
Buchanan later said: "I think Laguna just thought I would have went down the swanny dead easy because of the heat and what it was going to do to me, because he was Panamanian so he's used to the heat.
"He said to me 'I expected you to collapse after about seven or eight rounds -- when it hit the 11th or 12th round I kept on saying to my manager 'what's keeping him up?'
"I was completely shattered after the fight. Tears were running down my face because the person I wanted to be there was my mum, that's what she always wanted, to see me being a world champion. My dad and I held each other, greeting - I'd done it."In the documentary, Josh Taylor pays tribute to Buchanan – 50 years after he emulated his hero and mentor's great achievement of becoming an undisputed world champion.
Buchanan held all the belts in the lightweight division after he defeated Mexican Ruben Navarro in Los Angeles in February 1971.
Taylor, 30, from Prestonpans in East Lothian, became the first Scot to match the remarkable achievement in may this year when he defeated super-lightweight José Ramirez in Las Vegas.
He said: "I'd never heard of Ken Buchanan before I got into boxing, and when I found out who he was and what he had done I just became an instant fan.
"He walked in through the door one day. He started putting his wraps on and his old school white leather boots and he started hitting the bags - just watching him it was absolutely brilliant.
"I stopped training and just watched him. He still had the moves and I was like 'wow, that's the undisputed champ, right in front of me'."
Taylor also reveals his sympathy for Buchanan that he was never able to avenge his controversial defeat to Roberto Duran after the Panamanian ring legend twice broke agreements for a rematch.
He said: "For Ken not to get the rematch and be chasing it would definitely eat away at you, I know it would eat away at me."
Mickey Vann, 77, the former boxer and international boxing referee, also tells the programme: "Man's instinct is to fight - it's a natural instinct. Kenny to my mind was the greatest British fighter we've ever had.
"Kenny, in my eyes, will always be famous. He will always walk down a street and have people saying hello and wanting to shake his hand. The guy's a legend."
* Undisputed: The Life and Times of Ken Buchanan, is on Tuesday [SEPT 14], BBC Scotland 10-11pm