Scotland Yard spied for more than two decades on the partner of an anti-racist protester who police accept was almost certainly killed by one of their officers at a demonstration, a public inquiry has been told. Celia Stubbs campaigned for years to uncover the truth of how her boyfriend, Blair Peach, died at the demonstration. It was one of the most controversial cover-ups in modern policing history. Documents disclosed by the public inquiry revealed how undercover officers working for a secret Metropolitan police unit monitored the progress of the campaign that she and other activists ran. The spies recorded the names of people who attended Peach’s funeral. Photographs of those who attended were circulated among the undercover officers in order to identify other mourners. Throughout the years that the surveillance was taking place, the Met concealed a report of an internal investigation that said it could “reasonably be concluded that a police officer” struck the blow to the head which killed Peach in 1979. The report, which examined his death during the demonstration against the National Front in Southall, west London, was concealed for three decades until 2010. Stubbs and Peach’s family campaigned to gain access to the report for years. No officers were prosecuted over the death. On Thursday, Stubbs, 80, gave evidence to the judge-led public inquiry which is looking at the conduct of more than 139 undercover officers who were tasked with infiltrating political groups for more than four decades from 1968. She told the inquiry that the monitoring of her “was particularly unpleasant because while I was grieving the death of my partner and trying to campaign for justice for him, I was the subject of improper surveillance”. She accused the police of “abusing their surveillance powers. They deployed them not to protect the public from harm but to protect themselves from facing justice.” “They wanted to know what I was doing and what others who were helping me were doing, with the obvious inference that they did so to ensure that they stayed one step ahead of our campaign to hold Blair’s killers to account.” She called the surveillance of mourners at the funeral “very distressing”. In one of its strands, the public inquiry, led by Sir John Mitting, is given the job of examining how the police spied on a number of grieving families, mainly black, whose relatives had been killed by police or died in custody. Many are high-profile cases that created tension between the Met and minority ethnic communities for many years. The government set up Mitting’s inquiry after the Guardian revealed police covertly monitored the campaign for justice over the racist murder of Stephen Lawrence. In April 1979, Peach, a 33-year-old teacher from New Zealand, was killed as he tried to walk home from the anti-fascist demonstration. His skull had been crushed with an unauthorised weapon such as a lead-weighted cosh or police radio, according to one expert. At the time of the demonstration, police held files on Peach and Stubbs, both members of the leftwing group the Socialist Workers party, recording their political activities. The file on Stubbs dates from the mid-1970s. A day after Peach’s death, undercover officers in the secret Met unit, the Special Demonstration Squad, started logging details of the campaign to identify his killer. Other reports recorded the campaign’s protests, meetings and leaflets. The most recent report that recorded the monitoring of Stubbs dates from 1998 when campaigners began to organise the 20th anniversary of Peach’s death. In 2010, the Met published the report that concluded Peach had almost certainly been killed by an officer from its riot squad, the Special Patrol Group. Commander John Cass had led the internal investigation into Peach’s death as he was in charge of the Met’s internal complaints bureau in 1979. The inquiry continues.