A former undercover police officer has accused a colleague of lying about being beaten up by police while he was infiltrating leftwing protest groups in the UK, a public inquiry has heard. The officer alleged that his fellow undercover officer, John Dines, inflicted injuries on himself after he was arrested under his fake identity at a demonstration. Dines was also alleged to have carried marbles to the demonstration that he could roll under the hooves of police horses. Dines was accused of seeking “martyrdom” and to be seen as a high-performing undercover officer when he spent four years pretending to be an anarchist. The accusations against Dines were made at the public inquiry that is examining the conduct of undercover police officers who were sent to spy on more than 1,000 mainly leftwing political groups since 1968. Dines infiltrated anarchist and animal rights groups between 1987 and 1991. While undercover, he deceived Helen Steel, a social justice campaigner, into a two-year relationship. Steel was one of the defendants in the 1990s McLibel case. Dines told her that he wanted to spend the rest of his life with her, but then disappeared, claiming to be having a mental breakdown. Dines had concealed from her the fact he was part of a secret Metropolitan police undercover unit, the Special Demonstration Squad (SDS). However, Steel pieced together clues to expose his real identity years later. During his deployment, Dines was arrested when tens of thousands protested against the poll tax, a controversial policy to charge everyone a fixed local tax that led to widespread protests. In March 1990, hundreds of demonstrators were arrested and injured during some of the worst public disorder seen in central London for decades. Police used horses to quell the disturbances, during which a cloud of black smoke rose over Trafalgar Square. Many police officers and horses were injured. Dines was one of three undercover police officers who infiltrated the demonstration. Last week, Alan Nicholson, an undercover officer who had been a member of the SDS at the same time as Dines, gave evidence to the inquiry. Nicholson alleged that he was present when Dines reported to the SDS managers that he had been arrested and “allegedly beaten up in a police van on the way to the police station”. Dines “had carried marbles … and these could be used to roll under the hooves of the police horses, so it is not surprising that he was arrested having been stopped by the police”, Nicholson added. Nicholson said he believed Dines had set out to be arrested and beaten up by police. “The injuries that he sustained, in my mind, were not consistent with having been beaten up in the back of a police van. In other words, they were self-inflicted, in my opinion. “The injuries I witnessed on his face did not resemble being battered … no sort of grazing and skin being rubbed off.” Asked what had motivated Dines to lie, Nicholson replied that he wanted to be a “star”. He added that Dines “was out for martyrdom … He wanted to be a gold-star SDS officer.” Nicholson and Kevin Douglas, another SDS undercover officer, told the inquiry last week that Dines was a “gong hunter” – a competitive officer who wanted it to be known that he had performed well in infiltrating leftwing groups. Dines will have the opportunity to give evidence later this year at the inquiry, which is continuing. Steel became known for her involvement in the long-running McLibel trial. She and another environmental campaigner, Dave Morris, were sued for libel by the fast food giant McDonald’s over a leaflet they had distributed criticising the company’s practices.