The IRA used coded warnings as an alert to any device, therefore that threat was relatively overt.
Security services already have access to information whenever they deem it necessary as part of RIPA and also the Civil Contingencies Act.
So again why would they have to have the records of everyone when all they have to do is apply for the information, is it because they don't want to apply and would prefer to simply indiscriminately 'snoop'?
https://www.gov.uk/guidance/surveill...nter-terrorism