Blustery showers greeted racegoers as they began pouring into Epsom racecourse early on Saturday morning ahead of the 224th running of the Vodafone Derby.

The traditional double decker buses began lining the final straight as early as 8.30am with picnickers also reserving their spot along the rail as the atmosphere built up towards racing's blue riband, which is due to get underway at 4pm.

Bookmakers were expecting a deluge of bets on Irish-trained horses in the 20 strong field with the Aidan O'Brien-trained Brian Boru a popular choice to give the Irish champion trainer a unique third successive win in the race following the successes of Galileo and High Chaparral in the last two years.

His main rivals are both trained at the Curragh, with Dermot Weld's charge Refuse To Bend a big hope to supplement his success in the Sagitta 2000 Guineas while John Oxx will be hoping to repeat the success three years ago of Sinndar with Alamshar who runs in the same green and red colours of owner the Aga Khan.

"The overnight rain will probably affect Alamshar in the market more than the other two as he is a horse that prefers top of the ground conditions," said Dale Tempest, spokesman for internet bookmakers Sky Bet.

"Refuse To Bend will be suited by ground on the soft side of good and is expected to go off favourite ahead of Brian Boru who also likes to dig his toes in.

"The best supported horses British-trained horses have been Kris Kin, the mount of Kieren Fallon, (14-1) and Norse Dancer (22-1)."

The official going for the mile and a half test was described as good by clerk of the course Andrew Cooper.

Cooper said: "We have had no measurable rain this morning, just a few spits and spots.

"The ground is still good, though there may be some patches where it rides a bit slower and some where it is a bit faster.

"There is no forecast of any rain, so I expect that the track will dry out slightly and gradually through the day. I do not anticipate having to change the going."

Weld flew in with Refuse To Bend this morning and described the colt's final preparations as "perfect".

"He's travelled over well," he said. "I came over with him a few hours ago and he's all set."

The trainer also declared himself satisfied with underfoot conditions on the unique undulating track.

"It's absolutely beautiful ground and a credit to the staff at Epsom."

Weld believes his charge should win if he manages to stay the mile and a half trip. However, he is aware of the idiosyncracies of the course.

"Epsom is a law unto itself," he said. "We saw yesterday how unlucky in many ways Yesterday was."

Aidan O'Brien's charge finished a neck runner-up to Casual Look in the Vodafone Oaks after meeting traffic problems up the straight.

"You need all the luck in running. I think it's a very open Derby and I wouldn't be at all surprised to see one of the English outsiders feature strongly in the race," Weld continued.

"I'me hopeful, not confident. This is a big, big challenge today for this colt. We are running him, maybe, out of his true trip.

"But he's got so much class, so much speed that we are hopeful that he can carry his speed over the distance.

"He has the most speed of any horse in the race, so if he stays he should win."