Ante-post favourite Brian Boru heads the 24 colts remaining in the Vodafone Derby after Monday's confirmation and supplementary stages.

Aidan O'Brien's charge regained his position at the head of the betting on Friday after heavy support for the son of Sadler's Wells and negative rumours surrounding his market rival Refuse To Bend.

Brian Boru finished third behind two of Saturday's rivals, Alamshar and The Great Gatsby, on his reappearance in the Derrinstown Stud Derby Trial at Leopardstown.

"We were happy with his run," O'Brien told attheraces. "It was obviously his first competitive race this year. It was a little bit slower than we would have liked but he came home well and we've been happy with him since.

"He's a clever, very intelligent horse with a lot of natural ability."

O'Brien, who is bidding to win the blue riband for a record third year on the bounce following the victories of Galileo and High Chaparral, also has Alberto Giacometti, Balestrini, The Great Gatsby and Handel in the Epsom Classic.

As expected, Dutch Gold, Kris Kin and Norse Dancer have been added to the field at a cost to connections of £90,000 for each horse, giving the Derby a total prize fund of £1,470,000, making it the richest race ever run in Europe.

Clive Brittain could be double-handed in the Derby, having supplemented Victor Chandler Chester Vase winner Dutch Gold and left in his Italian Derby third Lundy's Lane.

Dutch Gold is a definite runner, but a decision on Lundy's Lane will be made later in the week.

The Newmarket trainer has been happy with Dutch Gold's progress since his six-length call over Derby rival Summerland on the Roodee.

He said: "Dutch Gold is in very good form. I'm delighted with the way things have gone.

"He'll be going there with a big chance."

Explaining the reasoning behind leaving Lundy's Lane in the blue riband, Brittain said: "We decided on leaving him in to have a look. A decision as to whether he will run will obviously be made before Thursday (final declaration stage).

"There were several factors. What was and what wasn't going to run, how many would be in? We were already in and we supplemented Dutch Gold at £90,000, and it was only going to cost £2,500 to have a look with Lundy's.

"We didn't throw the money away. He's very well in himself and he's taken his Italian run very well."

Officials at Epsom are keeping an eye on the weather before putting any more water on the Derby course.

Clerk of the course Andrew Cooper said: "We got four millimetres of overnight rain, which is about half of what we were forecast.

"The going is unchanged at good, good to firm in places. I'm perfectly happy with the ground at the moment but in a way I would have preferred to have a little more rain last night because it is forecast to be dry for the next 48 hours.

Some of the good to firm areas could be a bit quick by Wednesday.

"It is now looking like we might get some rain later in the week. We will just have to keep an eye on it and see how things go but at the moment I'm perfectly happy."

The dry conditions will suit Alamshar, who represents the owner, trainer and jockey team of the Aga Khan, John Oxx and Johnny Murtagh, responsible for Sinndar's Derby triumph three years ago.

"I think the firm ground would be important," Murtagh said discussing Alamshar's chances.

The safety limit for the Derby is 20, so four of those still in will not run and one of those who could be eliminated is the John Gosden-trained Summerland.

"He will be declared. We are keen to run him but he might not get in. He's on the borderline," Gosden said.

"J Fortune will ride. The horse worked this morning and worked well. His form links in well with Alberto Giacometti.

"Our horses are firing at the moment but we need to get in."

A Ladbrokes' telephone punter has had a £10,000 each-way Oaks and Derby double.

"Our customer has backed Alamshar at 4-1 and Hi Dubai at 7-2 to win £225,000," said Balthazar Fabricius of Ladbrokes.

"Alamshar is now 7-2 and it is refreshing to see some money coming for something other than an O'Brien-trained horse."

Vodafone Derby betting:

Ladbrokes: 3/1 Brian Boru, 7/2 Alamshar, Refuse To Bend, 10/1 Alberto Giacometti, 14/1 Kris Kin, 16/1 Dutch Gold, Norse Dancer, The Great Gatsby, 20/1 Magistretti, Shield, 25/1 Franklins Gardens, 33/1 Let Me Try Again, 40/1 Balestrini, Dunhill Star, Graikos, New South Wales, 50/1 Handel, Unigold, 66/1 Lundy's Lane, Summerland, 100/1 Prince Nureyev, Strength 'N Honour, 200/1 Albanov, 500/1 Skelligs Rock.