David Cameron confirmed today that he did ride a horse which was lent by police to former News of the World editor Rebekah Brooks.
The Prime Minister apologised for allowing a "confusing picture" to emerge over recent days about his direct connection with the animal.
He told reporters that the horse, Raisa, was among his mounts when he rode, before becoming Prime Minister, with Mrs Brooks's husband Charlie, a friend since they attended Eton school.
"I have not been riding with him since the election. Before the election, yes, I did go riding with him," he said at a press conference in Brussels.
"He has a number of horses and, yes, one of them was this former police horse Raisa which I did ride.
"I am very sorry to hear that Raisa is no longer with us and I think I should probably conclude by saying I don't think I will be getting back into the saddle any time soon."
The question of whether Mr Cameron rode Raisa became the subject of Westminster speculation this week after the loan by Scotland Yard to the ex-tabloid editor was made public.
After initially declining to directly answer questions, Downing Street aides conceded last night that the premier "probably" had mounted the ex-Metropolitan Police horse.
That came shortly after Number 10 had been forced to retract an earlier briefing that he had ridden with Mr Brooks after taking office in May 2010.
His spokeswoman also said that while he had "no recollection" of ever having ridden with Mrs Brooks, that could not be ruled out.
The case has refocused attention on the relations between politicians and newspaper executives, which Mr Cameron has admitted became too close over recent years.
Asked whether the case was emblematic of those overly close ties, Mr Cameron said: "I have known Charlie Brooks, the husband of Rebekah Brooks, for over 30 years.
"He is a good friend and he is a neighbour in the constituency. We live a few miles apart."
Details of the two-year loan of the horse were given last month to the Leveson Inquiry into media ethics which is currently scrutinising relations with the police.
Mrs Brooks, who resigned last year as chief executive of News International amid the furore over phone-hacking allegations, "fostered" the horse after it retired from active service in 2008.
She remains on bail after being questioned by detectives, days after resigning last summer, on suspicion of phone hacking and corruption.
She and her racehorse trainer husband paid food and vet bills until Raisa was rehoused with a police officer in 2010 - months before fresh investigations into illegal activities at the News of the World.
The force said the horse was returned in a "poor" condition and later died of natural causes.
Mr Cameron said in an interview yesterday that he had ridden once since becoming Prime Minister but Number 10 has declined to discuss the circumstances.
London Mayor Boris Johnson said he had not ridden the horse.
"I count myself proudly as a non-member of any kind of Chipping Norton set," he told BBC London, in a reference to the area of Oxfordshire where Mr Cameron and Mrs Brooks live.
Lord Justice Leveson hit out at leaks from his inquiry after details of the horse loan were disclosed in the London Evening Standard.
He warned today that, if the leaks continued, he could restrict advance release of witness statements to core participants - people who have a significant interest in the hearings or may face criticism.
"I am disturbed about it, not only because leaks would constitute a breach of the confidentiality agreement that everybody has signed, but also because it runs the risk of disrupting the way in which this inquiry can proceed," he said.
Mr Cameron has rejected Labour claims that the inquiry was being undermined by senior Tories, including Education Secretary Michael Gove who warned of a "chilling" atmosphere.
He gave his full backing to the probe, which he set up at the height of the hacking revelations last year - but said former journalist Mr Gove was right to defend the need for a strong Press.
"It's important for us to say we support a free, vibrant, robust Press. I do think that's an important point and that is what he (Mr Gove) was saying."
Labour's deputy leader Harriet Harman said: "People will be dismayed that while News International was busy hacking phones, David Cameron was out hacking with Rebekah Brooks's husband.
"David Cameron has not been straight about just how close he was to senior executives at News International and it's time for him come clean about the extent of this relationship."
Top Gear presenter Jeremy Clarkson, who is also associated with the "Chipping Norton set", claimed today that Mr Cameron had never ridden the horse in question.
Contradicting Downing Street's confirmation that the Prime Minister did ride Raisa, Mr Clarkson told Chris Evans on BBC Radio 2: "I can categorically state that he never rode that horse. I do actually live there. It's all rubbish."
Mr Clarkson, who writes newspaper columns for News International titles The Sun and The Sunday Times, was speaking before Mr Cameron himself admitted that he had ridden Raisa.
"I saw that horse and it wasn't badly treated as some people were saying, it was beautifully treated, it was only there for a very short time and David Cameron never rode it," Mr Clarkson said.
He added that he himself had never ridden it but Mrs Brooks "probably did and her husband did".