The North Yorkshire rider, 45, will hang up the saddle at Uttoxeter tomorrow where he is due to have four rides.
Career highlights include Kempton’s King George Chase on See More Business in 1997 – and the following year’s Cheltenham Gold Cup aboard Cool Dawn for trainer Robert Alner who was a great supporter of Thornton.
As well as staying chasers like Kingscliff, Sir Rembrandt and Miko De Beauchene, he also enjoyed big race success with top class hurdler French Holly who was trained at West Witton by Ferdy Murphy.
Yet Thornton also personifies perseverance and the increased longevity of jockeys as a result of advances in medical treatment, fitness and nutrition.
He rode his 1,000th winner at Wincanton on Boxing Day in 2016 – and promptly injured his knee as he dismounted from his victorious horse Kentford Myth.
However he made a successful comeback and earned the admiration of all in racing as he accumulated 1,005 winners following his first ever ride in 1990 for legendary County Durham trainer Arthur Stephenson.
“I’ve enjoyed every minute of it and I wouldn’t change anything, except I wouldn’t fall off so many and wouldn’t have had so many injuries,” said Thornton who has become an accomplished media pundit in recent years for ITV Sport, At The Races and BBC Radio 5 Live.
“It’s been a pleasure to be involved so long in a sport I love so much. I woke up on Thursday morning, had a few things running around in my head and I thought the time was right. It was as simple as that.
“I had a winner for Seamus (Mullins) at the start of the season, he’s having a good run of things but I’m not getting as many rides as I used to and I just felt I had to grow up. Father Time is catching me up and I’d like to do it on my own terms.
“I’m looking forward to Uttoxeter – it’s the right time for me, the right time for Seamus and time moves on, he’s got his owners to think about. I’ve got a lot to look back on. I rode my first winner on Wrekin Hill on November 22 in 1991, he was a cracking horse for me to get started on. I rode my first three winners on him. I owe WA (Stephenson) everything, I wouldn’t be where I am now without him.
“My wife asked me this morning if I was sure, but I absolutely am, I’ve no regrets. People talk about the end of an era, but I’ve probably spanned two eras. I’ve got four rides but even if one of them wins, I will be riding the fourth, simply because I love it.”
Next month’s Coral Eclipse Stakes could see the return of Epsom Derby hero Masar.
Though Charlie Appleby’s Derby hero holds an entry in the Irish Derby, the trainer is contemplating a tilt at the 10-furlong race which could also feature Epsom third Roaring Lion as the Classic generation take on older horses.
“I like to work back from the races we are looking at in the autumn such as the Arc and the Qipco Champion Stakes. He’s not in the Eclipse but we could supplement him,” said Appleby.
Harry Cobden faces a summer on the sidelines after suffering a neck fracture in a fall at Market Rasen. The teenager, already a three-time Grade One-winning jockey, was recently appointed number one jockey to former champion trainer Paul Nicholls.