The coalition government included in its May Conservative-Liberal Democrats coalition negotiations agreements, the following item in the Civil Liberties section:
Ending of storage of internet and email records without good reason.
In its Strategic Defence and Security Review – Securing Britain in an Age of Uncertainty (pdf) published earlier this week, the government announced it has apparently found a good reason:
We will: [...] introduce a programme to preserve the ability of the security, intelligence and law enforcement agencies to obtain communication data and to intercept communications within the appropriate legal framework. This programme is required to keep up with changing technology and to maintain capabilities that are vital to the work these agencies do to protect the public. Communications data provides evidence in court to secure convictions of those engaged in activities that cause serious harm. It has played a role in every major Security Service counter-terrorism operation and in 95% of all serious organised crime investigations. We will legislate to put in place the necessary regulations and safeguards to ensure that our response to this technology challenge is compatible with the Government’s approach to information storage and civil liberties.
This programme, formerly known as the Interception Modernisation Programme (IMP), was estimated to cost £2bn. Chris Williams, over at El Reg, gives some context in Green light for spooks' net snoop plan.
(This is obviously is in addition to the existing data retention programmes in place under the European data retention directives. See Voluntary electronic tagging for some thoughts on these.)