Yes lots of systems record that we have used an oyster card, made a phone call, taken cash out of a hole in the wall. And the police should have access to the records of these transactions in the pursue of serious crime. To argue that this information should not be accessed or not be available to the police is plainly stupid.
But there is the very real need for there to be appropriate controls on the access to and use of this information. So what we are relay arguing about in not the surveillance of citizens by the state it is the oversight and control of that information.
The law is based largely on the retrospective punishment for actions. You can only be accused of the things you have done, or attempted to do. Thinking about robbing a bank is not illegal, researching how to rob a bank is not illegal, the banks security staff do this all the time.
And the same should be true of a police investigation, it should be on the evidence of of acts that have been performed, associated with a reported crime.
Would you seriously say that the police could not have access to the Oyster records in order to see who had got on a train when someone was assaulted, to fine witnesses or the culprit. Or to the records of a mobile phone of an abducted person in order to locate them.
But what we do need to stop is the frivolous use of this sensitive data, and that requires appropriate oversight and control.
Exactly how to do this is what we should be talking about, not reducing the debate down to a big brother is watching you, remove all surveillance from society, type of slanging match.