In his left hand he was carrying a newspaper. His right hand was holding the strap on his backpack. As he brushed past a woman walking in the opposite direction, their shoulders colliding briefly, the 51-year-old thought nothing more of it.
The woman, an actress on her way to a rehearsal, later told police Mr Pearson sexually assaulted her. She offered details of how he "penetrated her" on the concourse of Waterloo Station despite the fact she was wearing "training pants" under a dress and despite footage showing he never broke stride.
Mr Pearson said the case against him was "preposterous", but still his name was dragged through the mud. For a year he defended himself in court and out of court. When he explained to people that it never happened like his accused said it did, he knew people were thinking: "Of course you would say that".
A jury spent just 90 minutes deliberating before finding Mr Pearson not guilty last week.
It came as a relief to the married picture-framer but the damage had already been done.
"Anybody who has seen the CCTV images knows that I couldn't possibly have done it," Mr Pearson said.
"It is against everything I believe in as a human being. I did nothing. I would have had to crouch down, put my hand up the woman's skirt ... penetrate her, take my hand out again ... all while holding the newspaper and walking along the concourse."
He says he now suffers from anxiety.
"For me, half a second turned into a year of hell. I feel I have undergone a form of mental torture sanctioned by the state."
The case was pursued by the Crown Prosecution Service despite no witnesses and no forensic evidence supporting the woman's claims.
Martin Daubney, the former editor of men's magazine Loaded, penned a passionate plea for common sense headlined: 'Stop treating all men as sex pests'. In it, he said Mr Pearson's case highlights a "misplaced war" on men.
"At ground level, men are being made to feel increasingly hated by a society and legal system that seems to say 'all men are capable of evil - if only you look hard enough'."
Mr Pearson's wife Carol said she knew all along that her husband was innocent, incapable of doing what he was accused of doing. On social media, users demanded the name of Mr Pearson's accuser be made as public as his.
A spokesman for CPS stood by the case against Mr Pearson.
"There was sufficient evidence for this case to proceed to court and progress to trial. We respect the decision of the jury."
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