The Intelligence and Security Committee of Parliament is today holding its first ever Open Evidence Session. The witnesses are the three heads of the UK intelligence Agencies: Sir Iain Lobban, director of GCHQ; Sir John Sawers, chief of the Secret Intelligence Service (MI6); Andrew Parker, director general of MI5.

The session, according to the Committee, “represents a significant step forward in terms of the openness and transparency of the Agencies. The Committee will be questioning the witnesses on the work of the Agencies, their current priorities, and threats to the UK.”

Yet, open public hearings on the role of the intelligence agencies is commonplace in the US and other democracies where the legislature has a much more established role in overseeing these agencies.

It is also worth noting which committee the troika of intelligence agency heads have agreed to speak in front of – not the Home Affairs Select Committee (led by a member of HM Opposition) – but a committee whose chair is picked by the executive. It is hardly as if the ISC are arms-length from the workings of the executive either, under the last government Hazel Blears MP was a former Minister of State at the Home Office, Paul Goggins MP was a Parliamentary Under-Secretary of State at the Home Office and two other members, Lord Lothian and Malcolm Rifkind MP have held positions at the Foreign Office.

With international tension mounting on the UK’s Tempora programme and growing European anger at the UK government for engaging in mass surveillance, will the committee do enough to scrutinise the programmes?

We will be live-tweeting highlights of the hearings @indexcensorship beginning at 2pm.