The new draft surveillance bill is like an iceberg, with a vast bulk of technical change obscured beneath the surface. Theresa May, the Home Secretary, presented the Investigatory Powers Bill to parliament as a measure "consolidating and updating our investigatory powers, strengthening the safeguards".

But it amounts to a dramatic alteration in the powers already available not just to the intelligence services, but to police, tax inspectors, and officials and regulators in almost every department of state.

If enacted, it would replace several pieces of complex and technical legislation.

The real issue is the tens of thousands of surveillance actions a day carried out by officials. The Bill is an iceberg. It is easy to focus on the sunlight glinting on a few peaks, it is harder to grasp the important bits beneath the surface. What is clear is that Parliament is expected to deal with all of this before the expiry of the Data Retention and Investigatory Powers Act at the end of 2016 – to swallow the iceberg before its dimensions can be fathomed.