Even a limited snooping bill is causing the Home Office trouble

David Cameron is giving a statement in the Commons this afternoon on, among other things, the Woolwich killing. He may well find himself answering questions afterwards about whether the government is planning to resurrect the Communications Data Bill, after a fierce debate in recess over whether it would have made any difference to the security and police services ability to stop the attack or to the investigation in the aftermath. The Lib Dem line remains that the party will not allow this legislation, and will only consider the very narrow issue of IP addresses.

But there have been some interesting negotiations taking place behind the scenes, I hear. One is that the Home Office is struggling to find a way of getting the data it needs from mobile phone browsers. This is a complicated process involving something called port address translation which needs to be applied with split-second timing. That timing is so sensitive that a millisecond can mean the difference between arresting the wrong person.