O'Brien reported after Dante win

The Ballydoyle trainer watched from County Tipperary as Cape Blanco galloped to second-favouritism for the Investec Derby, after which rumours circulated about his well-being.

Television pictures appeared to show the colt being lame and stiff, but representatives from Ballydoyle and Coolmore insisted the horse was fine.

In an attempt to settle the matter, stipendiary steward, Robert Earnshaw, and BHA vet, Lynn Hillyer, both spoke to O'Brien by phone but he was said to have refused for the winner to be examined and declined an invitation for his travelling head lad, Pat Keating, to meet with the stewards. Earnshaw said: "Our vet is down at the stables but Mr O'Brien has refused to have the horses trotted up in front of the vet. The lad has loaded the horse up and is heading for the airport.

"Mr O'Brien also refused a request for the stable lad to be interviewed by the stewards so the matter has been referred to the British Horseracing Authority under Rule B 83, which states that persons must comply with any instruction given by stewards at a race meeting."

Cape Blanco may have stated his credentials for the Derby, but his stablemate St Nicholas Abbey remains all the rage for the Epsom Classic.

With nine winners since 1958 completing the Dante-Derby double, bookmakers reacted to the O'Brien-trained Cape Blanco's taking success by initially installing him as the second-favourite for the blue riband on 5 June, before speculation of his well-being surfaced.

Ladbrokes went 5-1 from 12s and Coral 4-1 from 14, with St Nicholas Abbey shortening to 5-2 and 2-1 respectively at the head of the market.

St Nicholas Abbey, the dazzling Racing Post Trophy winner, may have failed to fire in the 2000 Guineas, but even stable jockey Johnny Murtagh was staying loyal after steering Cape Blanco to victory.

Cape Blanco was unbeaten in three starts as a juvenile and the 9-2 chance emerged as the convincing trial winner purists have craved as he pulled three and a quarter lengths clear of Workforce to provide O'Brien with his fourth Dante win – and his first in Britain this year after 15 consecutive losers.

Murtagh was delighted with the win and declared "crisis over" but St Nicholas Abbey remained at the front of his mind. "He (Cape Blanco) has got what it takes, but if the St Nicholas Abbey who ran at Doncaster turns up at Epsom then the rest are playing for places," said Murtagh. "Cape Blanco is unbeaten in four starts and is a very good horse. He is up there in the top four three-year-olds at Ballydoyle.

"You all know what I think about St Nicholas Abbey, but this guy has been there and done it in a very good trial."

The disappointment of the race was undoubtedly Godolphin's Chabal, who finished 16 lengths adrift of Coordinated Cut in fourth. Jockey Frankie Dettori said: "I can't put my finger on it. He was beaten four (furlongs) out. A good horse like that can't be that far wrong. It's very disappointing as we thought we had a Derby horse. It was too bad to be true."

Earlier, Michael Bell's 2009 Oaks heroine Sariska made an impressive return to action by making every yard of the running in the Middleton Stakes.

At York this afternoon, Henry Cecil's Manifest bids to continue his climb up the ladder when he tackles the Emirates Airline Yorkshire Cup.