British sprinter Bianca Williams, 29, and her partner, Portuguese 400m runner Ricardo dos Santos, 28, were followed and then pulled over by police outside their house in Maida Vale in July 2020 because officers said they were suspicious about how the vehicle was being driven.

Both athletes were handcuffed while they and the car were searched for weapons or drugs after officers said they could smell cannabis. They were separated from their three-month-old son, but nothing was found and no arrests were made.

Footage of the incident, which was widely shared on social media, showed Williams – a Commonwealth Games gold medallist – handcuffed and in a distressed state, leading to accusations that the couple had been stopped simply because they were black and in an expensive Mercedes car.

The incident occurred at a time when tens of thousands of people were demonstrating at “Black Lives Matter” protests in the UK following the death of George Floyd in Minneapolis.

London’s Metropolitan Police said an initial review indicated the five officers involved had not acted in a way that warranted disciplinary action.

However, the force later apologised for the distress caused to the couple and referred the incident to the Independent Office for Police Conduct (IOPC) because of the “significant public interest” in the case.

Two of the officers, constables Jonathan Clapham and Sam Franks, were found to have lied about smelling cannabis by a misconduct hearing, breaching expected standards of honesty. They face dismissal from the force.

Allegations against the three others, including that they breached police standards over equality and diversity, were not proven.

During the misconduct hearing, Dos Santos said he had feared for his family, and that had been stopped by police multiple times.

The lawyer for the IOPC said the athlete believed the officers were racist and he had been stereotyped because he was a black man driving a smart car. Dos Santos had been stopped nine times within four weeks of buying a car in 2018, the panel was also told.

Official government figures last month showed black individuals were four times more likely to be stopped than someone who was white.

The case is the latest embarrassment for London police which an independent review concluded in March was institutionally racist, misogynistic, homophobic, and unable to police itself.

The capital’s police chief Mark Rowley has vowed to clear up the force and said it needed to regain the public’s trust.