It is now illegal!
More worrying than the effect on amateur photographers, it will also curtail the activities of journalists.
You are already likely to be stopped by the police if you take photos of railways despite the fact that, as the link says, it's not even illegal.
This is the kind of stuff Stella Rimington is on about.
And taking photos of any kids that you are not related to could easily lead to serious misunderstandings.
What a great country we used to live in!