There's an excellent article on the law + photography in the February '08 issue (#69) of Digital Camera Mag, covering all aspects of shooting photography in public + also what you can + can't legally do with the photo's. It includes info on photographing children (in public and private), model/property release forms, copyright + more. It's a must-read article, as it raises issues which a lot of amateurs will not think to investigate but which could mean the difference between (inadvertently) breaking or keeping to the law.
As for a petition, TrooperUK, I do think it's time the gvt. openly clarified the laws, which are indeed vague to say the least, but can't help fearing that in pre-empting a public reaction from them, they will enforce laws which are even more restricting for the genuine photographer
PS The article I mention also covers your question on photography of buildings and landmarks from public locations.