A member of the public who caused a security alert when he bumped into David Cameron in Leeds has said he had "no idea" it was the prime minister.
Dean Farley said he was only aware that he had collided with Mr Cameron an hour after he had been arrested by police.
He insisted he was "not particularly political" and was just going out on his daily lunchtime jog to the gym when he ran into a "bunch of men in suits".
Mr Cameron has downplayed the incident, now the subject of a police review.
Mr Cameron was quickly driven away from the scene after the encounter outside the Civic Hall in Leeds.
West Yorkshire Police said "nothing sinister" had taken place but the Metropolitan Police, which provides personal security for the prime minister, said there would be a review of the incident.
The prime minister was in Leeds to launch government plans to upgrade rail links in the north of England.
A member of Mr Cameron's security team intervened as a man appeared to dart towards the prime minister. Officers then bundled the man away as the prime minister got into a waiting vehicle.
Mr Farley later revealed himself to be the man at the centre of the incident, saying he was not a protester and was totally unaware the prime minister was visiting the city.
"I didn't see David Cameron. I didn't know it was David Cameron until they let me out of the police van an hour later," Mr Farley, who was eventually released without charge, said.
The 28-year old said he was on the way to his local gym for a session with his personal trainer when he crossed the road outside the council building.
"All I saw were a group of men in suits who came out of the Civic Hall."
He added: "It begs the question - how good is Cameron's security if I managed to run between it before they stopped me?"
Mr Farley, who was carrying a towel but no ID at the time, said it had been "harrowing" to find himself "harangued and manhandled" by police and not being told why he had been arrested.
"I'm quite shook up. I was almost in shock, like I'd been in an accident or something."
The media reaction to the incident had been "insane", he said, adding that many of his friends wanted to buy him a drink and he could see the "funny side".
"I kind of wish I had been protesting something or I had had something to say", he added.
Following the incident, Chief Inspector Derek Hughes of West Yorkshire Police said: ''Around midday, a 28-year-old local man was briefly arrested after he came close to the prime minister's group who had just left the Civic Hall in Leeds.
''No threats were made, and after the man's details were checked, he was de-arrested and allowed on his way.''
The BBC's Tom Symonds said a member of Mr Cameron's party told him the prime minister stepped back as the man ran towards him and was not in contact with him.
The prime minister's close security is generally provided by officers from SO1 Specialist Protection, part of the Metropolitan Police's Protection Command.
Labour MP Keith Vaz said he would be "astonished" if there was not a review of procedures.
"It could have ended in a completely different scenario," he told Sky News, adding that Mr Farley's actions had caused a "great deal of concern".
But former Met officer Peter Power said that although "questions would be asked" about the incident, it was "not catastrophic" and was unlikely to lead to major changes.
He told BBC News that the fact that the man had been taken away so quickly showed the police response "worked reasonably well".
But former Deputy Prime Minister Lord Prescott, who punched a protester during the 2001 general election campaign after being hit by an egg, said the episode proved that security around top politicians needed to be "tightened up".
And speaking during a parliamentary statement on last week's EU summit, Mr Cameron jokingly made reference to the so-called "Prescott punch".
"I was actually in a meeting in Leeds speaking to a group of city leaders and other politicians and John Prescott was in the room as I gave the speech," he told MPs.
"And as I left the room I thought the moment of maximum danger had probably passed but clearly that wasn't the case."
Mr Cameron said he wanted to put on record the "debt" he owed to those who protect him on a daily basis, saying they did a "very good job".
It comes less than a week after a man threw a bag of marbles at the glass screen which separates the public from MPs in the House of Commons.
That incident took place during Prime Minister's Questions.