Theresa May, who was then home secretary, announced that there would be an inquiry into undercover policing and the operation of the Metropolitan Police’s Special Demonstration Squad (SDS). This secret unit, whose purpose was to infiltrate subversive groups, was set up in 1968 as part of Special Branch in response to protests against the Vietnam War. Only a handful of politicians, civil servants and senior police officers knew that the SDS existed; for 43 years, Parliament was told nothing. In 2010 an SDS officer, who under the alias Mark Stone had infiltrated the climate change movement,...…Theresa May, who was then home secretary, announced that there would be an inquiry into undercover policing and the operation of the Metropolitan Police’s Special Demonstration Squad (SDS). This secret unit, whose purpose was to infiltrate subversive groups, was set up in 1968 as part of Special Branch in response to protests against the Vietnam War. Only a handful of politicians, civil servants and senior police officers knew that the SDS existed; for 43 years, Parliament was told nothing. In 2010 an SDS officer, who under the alias Mark Stone had infiltrated the climate change movement,...WW…