The Serious Organised Crime and Police act of 2005(United Kingdom). This act was origionally designed to combat organised crime by creating laws to prevent racketerring/drugs trafficing/stuff like that. It did this by creating a specific police force to do this with.
However, sections 132-137 of this act more or less deny the right to protest in certain areas, they were put onto the act because the Government knew they would not succeed on their own but could not fail on this act.
A full map of these areas, and a list of the other areas it applies to, can be obtained from the metropolitan police's website, or by typing 'SOCPA' into Google images and looking for one with a map. These parts of the act have been widely criticized and challenged by some.
Many, myself incuded, beleive that this act was designed so that Tony Blair(or David Cameron for those reading this in a few year's time) would not have the embarrasment of people picketing against him outside the houses of parliament.
Another common beleif is that these sections were added to get rid of long-time protester Brian Haw, who has been camped outside the houses of parliament for the past 5 years(started early july, 2001-despite common beleif he did it after 9/11).
Despite this, it is still 'possible' to protest in the exclusion zones. To do this you have to give 7 days notification of the demonstration, say what it is about, how many people will be attending, where it will be and when. This might not be so bad on it's own, since notification is a relatively reasonable request for the purposes of policing. No, not too bad until THEY DECIDE wether or not to give you PERMISSION! This will no doubt be dependant upon your cause, and wether they agree. If you do manage to get permission, they will still put a time limit on the protest, a certain area for it to be held in(liek an animal in a cage, especially since they will use barriers), and a certain amount of people, we wouldn't want you to have to much support now would we?
If you are rich(i mean millionaire, not just 5 bed detached), you neednt bother with permission, since they will not choose to enforce this upon you. An example of this was recently when three directors caught up in the Enron scandle were due for deportation to the US, marched to the home office to protest, along with a large crowd of jackasses in suits, but were not challenged by the metropolitan police farce, even though their march was through the zone.
The latter part of the SOCPA act has been created for the sole purpose of crushing democracy and strangling the voice of the people.