Edwards, 63, was found by his brother, Terence, hanging from a steel girder inside the garage near Waterloo Station, south London, just after noon. Police said they were not treating the death as suspicious.
Widely known for his rehabilitation as a flower-seller at the station, Edwards served nine years for his part in the infamous raid on a Glasgow-to-Euston mail train in 1963. The robbers escaped with pounds 2.6m - the equivalent of about pounds 30m today - but the train driver, Jack Mills, was badly beaten in the process. He never returned to work and died in 1970.
Edwards went on the run with his share of the proceeds but surrendered to police three years after the robbery, apparently because of demands for money from the criminal fraternity. He was released in 1975 and opened his flower stall, where he had been seen by tens of thousands of commuters almost every day since.
But Edwards was said to hanker after his days as a criminal, and to be bored and depressed by his legitimate life. Staff at local pubs said he drank heavily.
According to witnesses, Edwards was at his stall as usual yesterday but looked ill and depressed. He asked a friend to mind the stall for a short while, but he never returned.
Graeme Bradley, a worker on the Jubilee underground line extension, may have been the last man to see Edwards alive. He said: ''When I saw him he looked very poorly, very ill-looking. I asked him what he was doing for Christmas and he didn't seem to know. A couple of hours later one of the lads came into the office and said he was dead''.
Speaking from Rio de Janeiro, Ronnie Biggs promised to ''have a couple of beers'' for Edwards, but he said he would not return for the funeral. ''It makes me very sad to learn that Buster has left us in this way,'' said Biggs. ''I always remember him as a jolly fella.''
In 1988, Edwards was plunged back into controversy with the making of Buster, a film starring the singer Phil Collins as Edwards. Critics argued it made a hero out of Edwards and glamourised a brutal crime. Piers Paul Read, who wrote a book about the robbery in 1978, said Edwards was the man who coshed Mills, although the police never established who struck the blow.
Phil Collins was ''very, very saddened'' by the death of Edwards, with whom he had become friendly. ''He always seemed up and he was a bit of a role model: someone having turned his life around. I'll miss him very much,'' said Mr Collins. ''Contrary to what a lot of people who haven't met Buster thought, he was a very warm person.''
Jack Slipper, the detective who tracked Biggs down to Brazil but failed to extradite him, said he was ''saddened'' by Edwards's death. ''I can't say I will miss him, but I am very very sorry to see a man take his own life.''
Since the robbers were captured, rumours have grown of a secret hoard, as much as half the money, that was hidden and never spent. Edwards's modest way of life suggested the rumours may have been false, but Biggs seemed anxious to keep the myth alive.
''He knew where the money was hidden, and he knew the names of the ones who were never caught,'' he said. ''So do I. We will all take that with us to the grave.''
The big mistake, page 26