Aidan O’Brien is one of the most decorated trainers in the history of Flat horse racing, although there are still certain races which have eluded the Irishman and that includes the Mill Reef Stakes.

This is a Group 2 encounter for two-year-olds and the latest renewal takes place on Saturday 21 September, with O’Brien hoping that a horse from his stable can show enough quality over six furlongs on what is likely to be firm ground.

Considering this race is for two-year-olds, there’s a certain amount of unpredictability that you don’t get with more established horses, although Monarch of Egypt is likely to be among the favourites if he lines up for the race.

We’ve seen this horse make three outings during the current Flat season, with Ryan Moore on board each time and it all started with a victory at Naas before two second-placed finishes at The Curragh in June and August.

On each occasion, Monarch of Egypt was beaten by American raider Siskin, although the latter will be nowhere to be seen at Newbury and perhaps this will give the former the chance to shine.

Harpocrates is another interesting runner for O’Brien who has been determined to get lots of racing into this particular two-year-old, although there has only been one win to show from his seven outings to date.

At the beginning of August, the horse scored a victory at Naas although the rest of the season has largely seen a series of near-misses and it’s likely that Ryan Moore will choose Monarch Of Egypt instead.

Arizona is the other O’Brien horse likely to line up and it should be noted that the two-year-old already has a glittering Group 2 success under his belt after winning the Coventry Stakes.

Moore rode the horse to victory as the 15/8 favourite on that occasion, with the horse having more recently had an engagement in Deauville, with the charge finishing a credible fourth in the Darley Prix Morny - Finale des Darley Series.

However, O’Brien might have to wait another year for a victory in the Mill Reef Stakes, with Mums Tipple likely to go off favourite and the Richard Hannon-trained charge has done little wrong in both outings this season.

There was a victory in a Maiden Stakes at Ascot in July before a step up in class saw the horse claim another win, this time in a Yearling Stakes at York, with the charge now bidding for a hat-trick of victories.

That win at the Knavesmire was seriously impressive, with Mums Tipple routing the field and Hannon admits that the horse has a number of different routes open to him.

Hannon said: "He's in all those nice races, the Middle Park, Champagne and in the Doncaster sales race, but he won't be going for that. He will probably go for the Middle Park or Mill Reef, but I'm not sure yet.

"He has taken everything fine. I've never seen a two-year-old win like that. He won the race coming out of the gate. He is a good horse. He needed the Ascot race, but that put him right for the other day."

He added: "He doesn't do a lot at home, but a lot of good horses are like that. "Paco Boy was like that, whereas with Canford Cliffs, whoever was riding him looked like they were on a jet ski.

"Mums Tipple is more like Paco Boy, but then he comes to the races and does something like he did the other day. He won that race with a 5lb penalty by 11 lengths - I haven't seen any horse win like that for a long time, let alone one of ours.

"The owners are really sweet and you do get a lot of job satisfaction when you see people like that enjoying their day."