Well said scot, criminals will be rubbing their hands because you won't get done for assaulting a police officer, and I'm one of them
Who says sf have only been used once? Im telling you, they and others arrest people all the time, on British soil, and mostly against British citizens.
As I said, when the home office says its ok, then it's ok.
For example, section 5 weapons are banned full stop, yet they can authorise you to have for instance a pistol. There is no real process, just authorisation.