Targeted monitoring is acceptable, the wholesale monitoring of the populous is not.
No-one knows (outside of the security services) what was known about these individuals. All that has been released is that they were on a list.
An attack of this type doesn't need a huge amount of planning. There is no need to co-ordinate with other perpetrators. There is no need for a huge amount of money to fund the operation. There is little need for any communication outside of the 2 individuals who have been shot and arrested.
You would need to be very careless to leave a trail for anyone to follow if you were planning an attack of this type. Anyone can get a knife or a meat cleaver from Tesco or Asda. Planning can be done over a beer while watching a movie. External communication is not needed.
So back to the article, Politicians of all colours want control, the security services need to have access to everything for the politicians to have the control they want. Just because there is a horrific incident does not justify wholesale surveillance.
Application of existing laws - incitement to (commit crime) should be applied to the people preach hate. Existing wire tap laws should be used where there is intelligence pointing to a crime.
Judges and the home secretary should remain in the path required to get a warrant to execute a wire tap/ internet monitoring.
With regard to the reference to Islam, NO religion on planet earth preaches hate. These people were acting outside of the teachings of their faith.