Trainer Aidan O’Brien continued his superb season as his filly Was won claimed a surprise Investec Epsom Oaks victory under Seamus Heffernan.

The 20-1 outsider won O’Brien his fourth Oaks and his third straight British classic after Camelot won the 1000 Guinneas and Homecoming Queen the 2000 Guinneas at Newmarket.

Was, sired by champion stallion Galileo, went clear early of the field and was never headed after overtaking Nayarra on the home straight.

She held off fast finishes from Shirocco Star and favourite The Fugue down the Epsom hill to earn her second career victory.

The market leader, The Fugue, owned by Lord Andrew Lloyd Webber, encountered a troubled race and was lucky to stay on her feet early on.

But her jockey William Buick found space round the outside to mount a serious challenge but he couldn’t reach the leading pair.

O’Brien’s fancied horse, Maybe, ridden by his son Joseph O’Brien struggled towards to rear throughout and was found out by the extended one mile four furlong trip.

The victory was O’Brien’s first since Alexandrova won in 2006 and after the race he praised the work of jockey Heffernen.

O'Brien said: "Seamus gave her a lovely ride, she came on lovely from her first run so we were delighted.

"She's a very good looking filly with a great pedigree. He's a great fellow, Seamus, a world-class jockey. He knows all these horses inside out and and nobody deserves it more."

O'Brien also revealed Was could have missed the entire season after a freak injury on the gallops.

"I was very happy with her in the spring but a shoe from a work companion hit her so I was worried she might miss her Classic season," he said.

"She was put back together with stitches in her leg and she was only just ready to run at Naas last time."

O’Brien will saddle the odds on favourite Camelot for The Investec Derby tomorrow aiming to extend his winning classics streak to four. He also has entered the third favourite Astrology to be ridden by former champion jockey Ryan Moore.

Earelier on Friday, Andrew Balding claimed a traning double as Side Glance won the group three Investec Diomed Stakes under Jimmy Fortune and Highland Knight led from start to finish with David Probert on board to win the Investec Mile.

The success will only boost Balding's market support for a Classic success as he saddles the Derby second favourite Bonfire tomorrow.