When and where?: Saturday (3.35pm) at Doncaster.
What Grade?: Group One
What Distance?: 1m 6½ furlongs
What Prize Money?: £743,000 (Winner: £424,191)
Age restrictions: For three-year-olds colts and fillies.
Weights & Allowances: Colts 9st 1lb; fillies 8st 12lb.
The St Leger is the oldest of the five British Racing Classics with the first renewal run in 1776, three years before the first Oaks was run at Epsom.
It was originally a two-mile contest before the distance was lowered to 1m 6½ furlongs in 1813.
Geldings could compete until 1906, but the race is now only open for colts and fillies.
Bill Scott remains the leading jockey in the race with nine wins between 1821 and 1846 and his brother, John Scott, is the most successful trainer with 16 victories between 1827 and 1862.
Key statistics and trends:
Great Voltigeur the key trial:
Will this year's Great Voltigeur hold the key on Saturday? Watch what our experts had to say.
Nine of the past 22 winners of the St Leger ran in the Great Voltigeur at York and finished in the top four. This year’s first and third, Old Persian and Kew Gardens, are set to line up on Saturday.
Other vital races this year:
Lah Ti Dar's win in the Galtres Stakes
Dee Ex Bee was runner-up in the Derby
Nine of the past 12 winners had at least one win in a Group One, Two or Three race.
Ten out of the last 12 winners had run at least five times and all winners had won at least twice.
The past 12 winners had at least three runs that season and 11 of them had at least one win that season. 13 of the last 16 winners had never run at Doncaster before.
Four of the past 12 winners were favourite/ joint favourite, three of those being in the last five years. 13 of the last 16 favourites have been placed.
The big guns:
15 of the past 22 renewals have been dominated by Godolphin (six wins), Aidan O’Brien (five wins) and John Gosden (four wins).
Irish Derby winner Capri just got the better of Crystal Ocean and Stradivarius to provide Aidan O’Brien with his fifth success in the race and his 18th Group One victory of his record-breaking season. It was also Ryan Moore’s first success in the British Classic.
O’Brien said: “He had a blip before York [registered a dirty scope] so we were a little bit worried coming here that he would improve for the run.
“He is a horse that has a lot of class and when Ryan really wanted him, he gave it to him.
“You never know what is going to happen and I was worried all the way until he crossed the line.”
It was the second time in six seasons that O’Brien won four of the five British classics, with Enable denying him a full house in the Oaks at Epsom.
2016: HARBOUR LAW
Harbour Law caused an upset, winning at odds of 22-1 in what a was a dramatic renewal.
The Aidan O’Brien-trained Idaho, who was sent off the 4-6 favourite, stumbled and unseated his rider three furlongs out when travelling powerfully behind the leaders under Seamie Heffernan.
Harbour Law stayed on strongly to get up close home and defeat 14-1 chance Ventura Storm by three quarters of a length.
Not only was it George Baker’s first win in a Classic, it was also trainer Laura Mongan’s, and she also became the first female trainer to win Britain’s oldest classic.
Speaking after the race, Baker said: “I can’t believe that! They have done everything right – they have given him plenty of time between his races and it has 110 per cent paid dividends for them. It’s an amazing feeling.”
2015: SIMPLE VERSE
Andrea Atzeni made it back-to-back wins in 2015 aboard Simple Verse but only after great drama.
Simple Verse was first past the post, defeating Aidan O’Brien’s Bondi Beach by a head, but the pair had something of a barging match and the Stewards’ reversed their placings.
Connections of Simple Verse appealed and, 11 days later, she was reinstated as the winner.
“We lose the race when clearly, whatever way you look at it, both horses leaned on each other,” Ralph Beckett said at Doncaster. “Can you honestly say that it was entirely her fault? Could you put your hand on your heart and say it was her fault in the last half furlong?
Beckett was relieved when Simple Verse belatedly got the race back but, understandably, the joy of her connections was tainted.
2014: KINGSTON HILL
Andrea Atzeni recorded his first success in the St Leger when he guided Racing Post Trophy winner Kingston Hill to victory.
The colt was held up in rear for most of the way before he gained the lead inside the final furlong and beat John Gosden’s Romsdal by a length and a quarter to justify favouritism.
It was also first success in a British Classic for Atzeni and trainer Roger Varian.
The Italian jockey was confident the whole way around aboard Kingston Hill. He said: “I rode him like the best horse in the race. He travelled beautifully. He’s so laid back, he goes to sleep. When I pulled him out, he was always going to get there.”
2013: LEADING LIGHT
The father and son team of Joseph and Aidan O’Brien teamed up to strike with Leading Light.
It was somewhat compensation for Aidan O’Brien as Camelot failed to become the first horse for 32 years to win the Triple Crown the year before.
It was a fourth win in the race for the Irish trainer and his first since Scorpion in 2005.
O’Brien said: “The lads have always thought a lot of him at home. I keep saying that it is a privilege to be involved with the team and we really appreciate having great horses to ride and train.
“It’s a big team effort and we are a very small part of it. I’m also delighted for Derrick (Smith, joint-owner) as Camelot ran in his colours last year and it wasn’t great.”
The Mahmood Al Zarooni-trained Encke, a 25-1 chance, denied 2-5 favourite Camelot the Triple Crown when he got the better of Aidan O’Brien’s runner by three quarters of a length and provided Godolphin with their sixth win in the race.
The following year Al Zarooni’s career ended in shame when he was banned eight years for doping Sheikh Mohammed’s horses. The ruler of Dubai said he would never work for him again. Encke was among the horses forbidden to run in 2013.
Encke’s success prevented O’Brien from becoming the first man to train all five British Classic winners in the same season.
The delighted winning-rider Mickael Barzalona said afterwards: “When I saw Camelot on my inside, I preferred to go right a little bit and try to run. My horse was very generous today.
“I kicked and asked my horse to go and he answered very quickly. I won very nicely. Today Encke was the best.”
2011: MASKED MARVEL
Masked Marvel stayed on powerfully to defeat Brown Panther and the hot favourite Sea Moon, who could manage only third, to record back-to-back wins in the race for John Gosden and William Buick.
Held up off a strong pace, the son of Montjeu travelled strongly before striding away from his rivals to win by three lengths. Buick even seemed to struggle to pull him up after the line.
John Gosden explained after the race that he always believed Masked Marvel would be an ideal candidate: “From the day I saw him purchased at Deauville as a yearling, I thought that he was that type (for the St Leger), if he grew and developed.
“He was a powerful little guy back then, but he has got great pedigree for this job and he has done nothing wrong all his life.
“We have other races we could have run in but, to win the oldest Classic with this horse is what we had planned for about two years, so sometimes it works.”
2010: ARCTIC COSMOS
22-year-old William Buick recorded his first British Classic success aboard Arctic Cosmos in 234th running of the St Leger in 2010.
It was a third win in the final Classic of the season for John Gosden, who trained the colt for his wife Rachel Hood and Robin Geffen.
Buick was seen as the most exciting young jockey around at the time and after the race said: “It is unbelievable - this is the victory we needed. We have had a good first season together (with Gosden) and I am really enjoying it.
“I am very fortunate to be in the position I am in. I am riding a lot of nice horses - there are a lot of good jockeys who deserve a chance too. I was always going to win, except if Nijinsky came from behind!”
Mastery provided Ted Durcan with the biggest British win of his career in 2009. The Godolphin second string lead home a one-two for the high-profile owners and trainer Saeed bin Suroor as he defeated Kite Wood under Frankie Dettori.
It was also a first British Classic success for the owners for five years.
Sheikh Mohammed had been a rare visitor to the tracks in previous months, but was in attendance at Town Moor, although may not have expected the result to be that way around.
He said: “I think one liked the ground and that was Mastery. Everybody in Godolphin works as a team. These are horses, not machines and they are flesh and blood. Sometimes there is sickness in the stable or something. The team is the same throughout the year. I am very proud of my team.”
After 25 failed attempts, Sir Michael Stoute finally got his name on the St Leger trophy when Conduit powered to a three-length victory under Frankie Dettori.
The 8-1 chance got the better of Irish-raider Unsung Heroine and Oaks winner Look Here was back in third.
It may not have been Stoute’s strongest chance on paper, however, as stable jockey Ryan Moore chose to ride Doctor Fremantle who finished eighth of the 14 runners.
Dettori, who was riding his fifth St Leger winner, said: “I said to Michael that you have had Lester Piggott, Walter Swinburn, Kieren Fallon and Ryan Moore and I was the last one on the list, but I have done it for you - well done Sir Michael.
“I have been there many times myself (in picking the wrong horse) - I have seen many races go the other way - it one of those things - you can only ride one horse and I was blessed that I was on this one.”