The big problem is how loosely the wording is on the new measures; its up to individual officers to use their judgement on the scene. In my 20 years on the streets as a news photographer I've across many descent, honest and mature Police officers. Sadly I have also come across a fair number of idiots who do not have the mental ability to handle the power, responsibility and importance the job of a Police officer entails.
If we're at the mercy of the latter kind, which sadly seems to increase by number as years go by, then many news assignments just cannot be covered properly any more.
I urge you to write to your MPs and to the papers objecting these ridiculous new powers. Its ridiculous that a press photographer with a press card can be considered a terrorist. One would assume that a terrorist would probably use a discreet camera phone or a hidden camera and not a couple of pro DSLRs and lenses.