OLVESTON-BORN trainer Paul Nicholls has confirmed that his greatest ever horse, Kauto Star, has retired.

The winner of two Cheltenham Gold Cups and five King George VI Chases, Kauto Star was pulled up on his final start in last season's Gold Cup.

Connections have taken time to make a final decision over whether the 12-year-old should race on, but the champion trainer and owner Clive Smith have decided to call time on his career. Speaking in his Betfair column, Nicholls said: "The end of an era has finally arrived. Clive was here this morning (Wednesday) and we have taken the decision to retire Kauto Star."

Nicholls revealed in September connections would consider giving the legendary chaser one last run in the King George at Kempton on Boxing Day, but after seeing him on the gallops in recent weeks, he feels now is the right time to draw stumps.

"We have had nine superb years with the horse but, after seeing him in his work these past few weeks, myself, Clifford (Baker, head lad) and Dan (Skelton, assistant trainer) were of the opinion that the time had arrived to retire him," Nicholls said.

"Of course, as owner, the final decision rested with Clive, but he agreed that the horse had done enough.

"Don't get me wrong, Kauto looks and feels as vibrant as ever, as those who saw him at our owners' Open Day last month would testify to. He was mad fresh that day and continues to be as alert as ever and very, very well in himself.

"But I suspect Kauto will be like that when he is 20-years-old. And, deep down, we know he has done enough - and in some ways I think we have to protect him from himself. And maybe ourselves, too. If he did go to Kempton and win or run well, would you really want to run him - or be able to resist the temptation - in the Gold Cup? I am not so sure."

Similar questions about whether Kauto Star should be retired were asked last summer, after he was pulled up in the 2011 Punchestown Gold Cup. But he proved all the doubters wrong with a scintillating comeback win in the Betfair Chase at Haydock before claiming the King George yet again.

"Kauto is signing off in full health and after a season in which he proved so many people wrong by winning a fifth King George and a fourth Betfair Chase, to add to his two Cheltenham Gold Cups and Tingle Creeks," said Nicholls.

"Who wouldn't want to train a horse of this quality any more? He is a once-in-a-lifetime horse, after all."

Nicholls added: "But whatever the future holds, I am certain that Clive and all us here at Ditcheat will reflect on a magnificent past and I am sure we will both go on searching for the unattainable in the future. Namely, a horse to replace the irreplaceable legend that was, and is, Kauto Star."