Nicknamed the “Choirboy”, Swinburn partnered Shergar to glory in the 1981 Derby at the age of 19, one of three winners for him in the Epsom Classic alongside Shahrastani (1986) and Lammtarra (1995).
Many other big-race successes around the world adorned his CV before his retirement in 2000.
Swinburn took over the training licence from his father-in-law, Peter Harris, in November 2004, sending out over 260 winners from his Hertfordshire base before handing in his licence at the end of October 2011, citing financial reasons.
Harris said: “I’ve been in Scotland all day and got home this evening and all I know is that he has died. I don’t know any more details at the moment.”
After his riding days were over, Swinburn enjoyed a successful period as part of the Channel 4 Racing team, working with former National Hunt great John Francome among others. Francome told At The Races: “I spoke to him a couple of months ago and he seemed in really good form. It’s absolutely shocking he should die aged 55. No age at all.
“He was an absolutely gifted rider, you never saw any horse pulling with him or having their head in the air.
“He was a little bit of a troubled soul in some ways, he had weight problems which probably affected him a lot more than other people, but that said that seemed to be a long time ago and he seemed to all intents and purposes fine, but obviously he wasn’t.
“He could ride a race, he had a really good feel for what was going on underneath him, hat the horse was doing.
“He’d give great feedback and come back in and tell you everything you needed to know. “He was a very sensitive person, both on and off a horse.”
Swinburn suffered a terrible fall at Sha Tin in February 1996 when his mount Liffey River crashed through the rails and was in intensive care for a week with severe head and chest injuries.
He returned to win on his first ride back on Talathath at Windsor just six months later.
Francome added: “It was a shocking fall, and he made an amazing comeback – but he was happiest on a horse. “He was great company and gave great insight (during TV coverage). He had a good smile, great sense of humour, fabulous parents – just a really nice family and I’m devastated for them.”
Meanwhile, trainer Jim Best has been given a six-month suspension, with no financial penalty, by a British Horseracing Authority disciplinary panel following a rehearing into the running and riding of two horses last December.
The panel ruled Best had instructed conditional jockey Paul John to ride Echo Brava and Missile Man other than on their merits and that they were “stopping rides”.
Panel chairman Sir William Gage said: “That being so, the findings against Mr Best under Rule (C) 45 in respect of both races necessarily follow because he did not give his jockey proper instructions.”
The Lewes-based handler, who denied all of the charges, was originally found in breach at a hearing in February, leading to a four-year disqualification. But it emerged the chairman of the disciplinary panel at that hearing, solicitor Matthew Lohn, was engaged by the BHA on other matters, giving rise to claims of an appearance of bias.
Best has seven days in which to appeal the new verdict.