That loss effectively forced his retirement from the sport although he did later attempt a comeback - which lasted only two fights. Lewis meanwhile went on to rule the heavyweight division and become a multi-millionaire.
"You have to remember that Lennox is Britain's best ever heavyweight and in the top 10 of all time," boxing pundit Steve Bunce told BBC Sport.
"Gary was ranked number three by the WBC at a time when there were terrific heavyweights around."
Lewis himself added on
"My bout with him was a watershed moment in my career and I'm truly grateful to have known him."
Following his retirement Mason, a carpenter's son from Clapham, was down but not out. The Jamaican-born Londoner was not the sort of character who would sit around and feel sorry for himself and he led a varied life after his boxing career.
A spell as a pundit for Sky Sports was cut short after he swore on television. He also played three matches for rugby league side London Broncos, scoring a try in his first game, and also appeared in television shows Gladiators and The Detectives - where he starred in an episode called 'Sparring Partners' alongside Jasper Carrott and Robert Powell.
Boxer Gary Mason in action
Mason also attempted to launch an arm-wrestling competition, and worked as a security guard for a hospital.
More recently the 6ft 2in ex-fighter was running therapeutic hand drumming workshops after setting up the Rhythmical Empowerment Group.
He was also a founder member of the Bunbury Celebrity Cricket team where he was known as a "crafty bowler, mighty batsman and heavyweight fielder".
Even before he became British champion he had a jeweller's shop rejoicing in the name of "Punch 'n' Jewellery" and turned his hand at promotion calling himself "England's version of Don King".
"Gary was a great maverick and a lovely fella. He did lots of things and tried his hands at lots of different businesses and was just a ducker and a diver," added Bunce.
He once claimed to have made £700,000 from boxing but estimated he was £80,000 in debt two years after his retirement.
However, despite the way things turned out, Mason remained positive until the last, with former sparring partner Glenn McCrory describing his friend as a "larger than life character".
Mason lost once in 38 fights, against Lennox Lewis in 1991
Sports agent Dave Davies, who looked after Mason in the mid-1990s, added: "Gary was always looking for a pound note.
"If there was ever anybody who would say, 'This time next year I'm going to be a millionaire', it was him.
"He decided he wanted to be a media star. He wanted to do after-dinner speaking and to open gyms. Unfortunately he was very much in the shadow of Frank Bruno."
His appeal was far reaching and the shock news of his death has been felt outside the world of boxing with Olympic cyclist Bradley Wiggins paying tribute to Mason on his
calling him an "inspiration".
"Even when I went down to the job centre, people kept asking for autographs, it was embarrassing," Mason once said. It spoke volumes of his personality.
Bunce added: "He didn't have a bad bone in his body - apart from when he was in the ring. There was no malice to him, he was just genuinely a really nice guy."
In all, hard-hitting, barrel-chested Mason fought 38 times and became British heavyweight champion in 1989, winning 34 of his fights by knockout. He retired in 1994 after 10 years in the sport.
Mason appeared in an episode of The Detectives called 'Sparring Partners' alongside Jasper Carrott
"If he was around today he would have dominated the heavyweight division," admitted promoter Frank Maloney.
But Mason was around at a time when the heavyweight division was particularly strong.
However, he still recorded victories against the likes of Tyrell Biggs, James Tillis, Lorenzo Boyd, Alfonzo Ratliff, Ricky Parkey, Donnie Long, James Pritchard, Mark Wills, Everett Martin, Louis Pergaud, Hughroy Currie, Terry Armstrong, David Jaco and Jess Harding and at one time was ranked among the top 10 heavyweights in the world.
"Gary was old-school, he learnt his trade the tough way and fought in hard 10-round fights against a lost breed of American heavyweights who just no longer exist," added Bunce.
"They were proud and came to fight and not fall over. He had real, solid, hard fights and that was the only way a fighter learnt back then, especially in heavyweight boxing.
"He was a bit old-fashioned, he belonged to a different period and a different time."
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