Two elected Green politicians spied on as “domestic extremists” joined a lawsuit yesterday against Scotland Yard’s sprawling surveillance database.

London Assembly member and peer Jenny Jones derided “pointless” snooping after she and Thanet councillor Ian Driver filed witness statements in support of 89-year-old Brighton pensioner John Catt — a fellow “domestic extremist” with a case before the supreme court later this year.

Scotland Yard’s deputy commissioner Craig Mackey told Ms Jones under direct questioning at a London Assembly last November that he was “confident” their secretive National Domestic Extremism and Disorder Intelligence Unit abided by police guidelines: “if it’s not appropriate to be kept for policing purposes, it’s weeded and it’s gone.”