An undercover police unit that monitored political groups over 40 years gathered intelligence on members of at least five trade unions, a whistleblower has revealed. Peter Francis, who spent four years undercover infiltrating political activists, has named five trade unions whose members he spied on: Unison, the Fire Brigades Union, Communication Workers Union, National Union of Teachers, and the National Union of Students. Francis, who has become a whistleblower in recent years ... was part of the covert Metropolitan police unit, the Special Demonstration Squad (SDS), that monitored hundreds of political groups between 1968 and 2008. Francis gave a statement to a packed meeting in Parliament that marked the launch of a new book about the blacklisting of thousands of workers by multi-national construction firms. This month, the Daily Mirror revealed that one of the undercover officers in the SDS, Mark Jenner, posed as a joiner and was a member of the construction workers union, UCATT, for three years. Jenner's involvement in trade unions is detailed here by the Undercover Research Group, a resource on covert infiltration of political groups. It describes how he attended meetings of UCATT and other unions, regularly went on pickets and ferried trade unionists to demonstrations. In his statement ... Francis said, "Let me state very clearly that Mark Jenner was 100% one of my fellow undercover SDS police officers deployed alongside me in the 1990s."