Just four yards will be represented in the Betfred St Leger on Saturday and there won’t be a Group One winner going to post.

Five of the nine in the race have run in a handicap this summer, which also tells you something about this year’s edition.

Aidan O’Brien runs a quartet, with John & Thady Gosden having a trio. William Haggas and the Crisfords also have contenders, so one of two training establishments (Ballydoyle or Newmarket) will be celebrating.

This still looks an intriguing renewal and will be notable for Frankie Dettori having his final Classic ride, barring comebacks. He's had an a dilemma choosing between Arrest and Gregory, with the rain that has fallen at Town Moor this week tilting him towards the former.

Here’s a guide to all the runners.

1 ALEXANDROUPOLIS

Trainer: Aidan O’Brien. Timeform rating: 112p. Odds: 25-1.

Positives: Bred for this test, being by Camelot, runner-up in the 2012 St Leger, out of a dam who was a half-sister to Kew Gardens, the 2018 Leger winner. Won on his sole start at two and there’s a suspicion we’ve not seen the best of him in two starts this year, almost five months apart. His powerful stable can do little wrong and seeks a seventh success in this race.

Negatives: Mountain to climb on form. He seemed beaten on merit in the Ballysax Stakes on his return and beat only one home in a seven-runner Listed race last time, albeit he didn’t get much luck in running. It’s possible he’s in here as a pacemaker for better-fancied stablemates.

What they say - Aidan O'Brien: "Alexandroupolis was second in a Derby Trial and then suffered a setback. We’ve always liked him and think he’s come forward plenty from his last run but will probably come forward more after this.”

Verdict: Bred for this test and is a possible improver, but easy to look elsewhere.

2 ARREST

Trainer: John & Thady Gosden. Timeform rating: 128. Odds: 9-1.

Positives: His only defeat as a two-year-old came when touched off in a Group One in France (Adelaide River well adrift in third) and this year he’s gained decisive Group Three wins at Chester and Newbury. Stamina looks his forte and the rain that has hit the track this week, plus forecast for Thursday, is very much in his favour as he’s been at his most effective on good ground or softer. Frankel, his sire, has had two St Leger winners. Frankie Dettori's decision to ride him in preference to Gregory speaks for itself.

Negatives: Disappointed when favourite the Derby, when not looking at home at the track or the fast ground. He also fluffed his lines at Royal Ascot soon after. There’s a sense he’s made the most of good opportunities, in lesser company, when winning this year.

What they say - John Gosden: “We’re very pleased with Arrest, he took his race very well at Newbury. He’s in top order but I think if it’s good-to-firm at Doncaster I think you’ll find him heading to Paris for the Prix Chaudenay rather than Doncaster. He’s a lovely horse but he rolls his knee and he’ll enjoy more what I call the autumn ground.”

Verdict: Would be interesting if the ground turned softish, although his price would contract.

3 CHESSPIECE

Trainer: Simon & Ed Crisford. Timeform rating: 124. Odds: 12-1.

Positives: Yet to finish outside the first three in any of his six races and he’s improved with every run, reflected by his official rating gradually rising from 96 to 109 since mid-May. Proved his stamina for the St Leger trip when third to Gregory in the Queen’s Vase and stuck to his task resolutely when beaten a neck by Desert Hero in the Gordon Stakes last time. This galloping track promises to suit and he may well have more to offer. Seems versatile regards the ground.

Negatives: Needs to raise his game. Has five lengths to find with Gregory on Queen’s Vase running and Desert Hero looked like mastering him some way out at Goodwood, beating him with a bit to spare.

Verdict: Likely to give it another good go, but looks vulnerable on form.

4 CONTINUOUS

Trainer: Aidan O’Brien. Timeform rating: 132. Odds: 3-1.

Positives: Two out of two as a juvenile and back to winning ways with a bang at York last time, when a commanding winner of the Great Voltigeur. That form has plenty of substance, too, with the runner-up, Castle Way, having previously won the Bahrain Trophy, and the third, Gregory, having won the Queen’s Vase. Shapes as if he will stay beyond 12f and seems at home on all ground. The only time he has raced in his native Ireland was on his debut, so he’s done plenty of travelling.

Negatives: There seems little doubt he benefitted from being held up in a strong-run race at York, with the leaders wilting. There’s a suspicion that things rather fell in his lap. He had been beaten in his three previous races, not screaming out as a St Leger candidate until last time. Unproven beyond 12 furlongs and not sure he wants such a stiff test of stamina.

What they say - Aidan O'Brien: “Continuous is very well. He came out of the race (Great Voltigeur Stakes) very well. He’s a horse that has class and you can take your time with over one-mile-and-six furlongs.”

Verdict: Predictably popular after his York success but got a canny ride that day. Stamina to prove.

5 DENMARK

Trainer: Aidan O’Brien. Timeform rating: 118. Odds: 50-1.

Positives: Lightly raced and has returned from five months off with two solid handicap runs – including when trying to give 4lb to Middle Earth over the St Leger trip at York on his penultimate start. He backed that up when third in another handicap at Haydock on Saturday.

Negatives: Looks the weakest link among his stable four possibles, with blinkers failing to help him get to the next level. He’s hung on a couple of occasions, including last weekend, not looking the easiest of rides. Trainer had suggested he was an unlikely runner but he'd been declared.

Verdict: Looks to be making up the numbers.

6 DESERT HERO

Trainer: William Haggas. Timeform rating: 124. Odds: 11-2.

Positives: The Royal runner arrives very much on the up, taking the Gordon Stakes in good style at Goodwood last time after winning a competitive handicap at Royal Ascot. He’s been strong at the finish of his races over 1m4f and that, coupled with the stamina in his pedigree, suggests the trip will be within his compass.

Negatives: There’s no doubt he’s come a long way since his unimpressive win in a novice event at Redcar last autumn, when long odds-on, but he was taking advantage of a mark of 94 at Ascot and his Goodwood win lacks a bit of depth. His sire, Sea The Stars, has had several fancied St Leger runners, including Stradivarius, but none have won.

What they say - Tom Marquand jockey: “He ticks all the boxes of what you want from a Leger horse. It’s 1m6f but he has speed, he stays, he relaxes right and he’s with the right team, so fingers crossed we get a good draw and the right trip around.”

Verdict: Has the right kind of progressive profile bit likely he will need more again.

7 GREGORY

Trainer: John & Thady Gosden. Timeform rating: 127p. Odds: 5-2.

Positives: The Golden Horn colt is out of Gretchen, a daughter of Galileo who signed off her short career with victory in the Park Hill Stakes over the St Leger course and distance in 2015. She was herself a half-sister to Duncan, the Irish St Leger winner. Gregory was unraced at two but has quickly made up for lost time, making it three wins from as many starts when landing the Queen’s Vase at Royal Ascot. Surrendered his unbeaten record in the Great Voltigeur after a break, but there were mitigating factors, including dropping back in trip and overly aggressive riding tactics under a penalty. That race should have added an edge and he will appreciate moving back up in trip, with the long straight tailor-made for him.

Negatives: Continuous had too many gears for him and if this is anything but a true test, he could again be outspeeded when it matters most. Softer ground is an unknown for him and Dettori has rejected him, so he will have a new jockey (Kieren Shoemark) on his back.

What they say - John Gosden: “He went a little quick early [at York]. When I saw the early fractions, I thought ‘we’ve just gone inside 12 seconds for a furlong’. You’re not going to do those fractions over the first three furlongs and finish your race. It was obvious where the winner came from, he was 20-lengths out the back. He actually ran a very good race and when Frankie put his hands down he galloped out well to the line. I’m very pleased with him at this stage, he seems in great order and very content in himself. He’s got a great mind and he is a pretty laid-back character. I trained both the mother and father and he’s inherited all their good traits of their mental attitude towards racing.”

Verdict: Looks a big player here despite his York reverse.

8 MIDDLE EARTH

Trainer: John & Thady Gosden. Timeform rating: 121p. Odds: 13-2.

Positives: Didn’t make his debut until mid-June, so he’s clearly open to more improvement just three months into his career. His narrow defeat of Naqeeb at Newmarket in late July has been franked (the runner-up won off a mark of 100 last Saturday) and he was impressive when following up in the Melrose at York, powering home from off the pace (off a mark of 93). It's a tip in itself that his connections have supplemented him and it’s worth noting the yard won this year’s Gold Cup at Royal Ascot with a horse who had won a handicap, off a mark in the 90s, on his previous start.

Negatives: Was clearly something of a handicap snip at York and this jump up to Group One company is unconventional. If this were a handicap, he’d be getting weight off plenty of these, including 13lb from Continuous. Having had only four runs, others are entitled to be more streetwise in what is always a tough race.

What they say - John Gosden: “Middle Earth ran a lovely race in the Melrose and I’m really happy with him. I think Oisin (Murphy) was very impressed with him. He hit the line strong. It’s the last Classic of the year and it’s three-year-old’s over a trip. He’s proven he stays the trip which let me tell you, the 1m6f and the yards tests the tactical speed and the stamina. He looks like he should be able to answer those two calls.”

Verdict: Has more on his plate but none of us know where his ceiling might be.

9 TOWER OF LONDON

Trainer: Aidan O’Brien. Timeform rating: 125p. Odds: 11-1.

Positives: The Galileo colt’s eight siblings, all daughters of Dialaflora, include Capri, winner of the Irish Derby and a vintage St Leger (Crystal Ocean and Stradivarius were the placed horses) in 2017. Tower Of London won a Listed race at Leopardstown in June and was most polished when forging clear in the 1m 5f Ulster Derby, off a rating of 99, at Down Royal next time. Was then backed off the boards for the Bahrain Trophy at Newmarket but that race favoured speed, rather than stamina, and he lost out by a head to Castle Star. Ryan Moore dropping his whip didn't help that day. A truly-run race over 1m6f should unlock more improvement and the fact he’s had a longer time off the track (65 days) than any of his rivals is not a worry. Interestingly, Capri had been off 77 days off before landing this Classic. Scorpion, another winner of this for O’Brien, had been off 58 days.

Negatives: His bare form suggests he's got a bit to find and he’s yet to record any kind of decent speed figure. You could argue he was betrayed by a lack of tactical speed when getting beaten last time, which is also a niggle. Ryan Moore seems more likely to partner Continuous.

What they say - Aidan O'Brien: “Tower Of London just got beat at Newmarket. He will get the trip, he’s a brother to Capri. He handles good ground and we’re very happy with him.”

Verdict: He’s rather slipped under the radar and is interesting at double-figure odds.

ANDY'S 1-2-3:

The Great Voltigeur is often they key trial for this race and Continuous, who won last month’s renewal, and Gregory, who was third, have to be near the top of any short list. I fancy Gregory to turn the tables but the one who makes most appeal, at the prices, is Tower Of London. His brother Capri, won the St Leger in 2017, and the Galileo colt has shown enough to think he may be able to emulate him. There's definitely more to come from him granted a true test. If the ground is genuinely soft on the big day, that would bring Arrest into the picture. However, dry weather is forecast for Doncaster on Friday and Saturday.

1 TOWER OF LONDON. 2 GREGORY. 3 MIDDLE EARTH. 4 ARREST