NOBODY should be surprised that Britain’s intelligence agencies collect and use confidential information passed between lawyers and their clients.

In reality there are no effective limits to what the Security Service (MI5), Secret Intelligence Service (MI6) or eavesdropping centre GCHQ can do in the name of the “national interest” and “national security.”

Only informed public opinion and the danger that it might demand some democratic control over them has ever prevented these agencies from going even further than they do.

Indeed, the Investigatory Powers Tribunal (IPT) which heard these latest revelations on Thursday only exists at all because former MI5 officer Cathy Massiter and investigative journalists such as Duncan Campbell revealed the extent of MI5 buggings and burglaries in the 1970s and early ’80s.

Then, the main targets of intensive state surveillance and disruption were communists and other political activists in the trade unions and CND, whose perfectly legal activities were being monitored to assist the economic interests of employers and the political interests of governments.

In response to widespread anger and concern, a series of laws placed the intelligence agencies on a legal footing for the first time, and erected a bogus facade of “accountability” which included the tribunals that were merged into the IPT in 2000.

Of around 250 complaints against state surveillance submitted to the Security Service tribunal up to that merger, not one was upheld. The precise number of cases is unknown because even that was adjudged to be a secret for the first three years.

Since then, the IPT has considered around 1,629 complaints about official surveillance, including by other government departments, local authorities and the police.

Only 10 have been upheld, none of them against MI5, MI6 or GCHQ.

The details of almost all of some 2,000 cases have been kept secret. Complainants are denied any information relating to the intelligence agencies about their complaint, the tribunals do not provide reasons for their rulings and the whole apparatus is exempt from the Freedom of Information Act.

Presiding over this travesty of justice is Old Etonian Mr Justice Burton, late of Balliol College, Oxford.

The annual reports by him and his predecessors exude Establishment smugness, making a meal of minor technical “errors” by the spy agencies while assuring us that everything is hunky-dory when it comes to gross infringements of our democratic liberties.

With the Westminster Parliament’s intelligence and security committee usually meeting behind closed doors, reporting secretly to the Prime Minister and issuing only highly censored summaries of its deliberations, Britain’s secret state knows it is free to tap phones, intercept mail, break into buildings, plant bugs and monitor the online activities of millions of citizens without let or hindrance.

No wonder MI5, MI6 and GCHQ chiefs are so angry with Julian Assange, Chelsea Manning and Edward Snowden for exposing the mammoth scale of their operations.

Most people agree that extraordinary measures may be necessary to protect civilians from terrorist attacks.

But the secret state still targets political dissidents, trade union activists and other non-violent campaigners as well, while keeping an eye on almost everyone else.

The intelligence services should not be allowed to undermine our hard-won democratic freedoms on the pretext of defending them.

This latest scandal underlines the need to bring the spies and buggers under control as part of a much wider programme to democratise Britain.