TWO Green Party politicians brought a case to the Investigatory Powers Tribunal yesterday over claims that they were put under surveillance by GCHQ.

The case has been launched by MP Caroline Lucas, who represents Brighton Pavilion, and London Assembly member Baroness Jones of Moulsecoomb.

Lawyers for the pair allege that their communications are being intercepted as part of the Tempora programme, which monitors and collates all electronic communications data produced in or transiting through Britain and other countries.

They argue that the surveillance is in breach of the Wilson Doctrine and parliamentary privilege.

The doctrine, introduced by prime minister Harold Wilson in 1966, says that no MP’s telephone should be tapped unless there is a major national emergency.

Before the two-day contested hearing in London, Rosa Curling of law firm Leigh Day said: “It is crucial that parliamentarians are able to have confidential communications with their constituents.

“There must be proper judicial oversight in relation to any surveillance that the intelligence services may wish to undertake of parliamentarians’ communications.”

Baroness Jones said: “As parliamentarians, our job is to hold ministers to account. If our communications are subject to blanket surveillance and people are less able to freely contact us with important and sensitive revelations, then our ability to do our job is hugely curtailed.”

Ms Lucas, for her part, said: “My constituents have a right to know that their communications with me are free from blanket monitoring.”

Former MP George Galloway has filed a separate case, which has been incorporated with that of Ms Lucas and Baroness Jones.