Have a look at RIPA, one important bit of law that regulates GCHQ: http://www.legislation.gov.uk/ukpga/2000/23/contents
Here's an example of GCHQ being mentioned as exempt from a law. This is the sexual offences act; GCHQ are allowed to "make"[1] a photograph of child sexual abuse if it's needed for a function of GCHQ. http://www.legislation.gov.uk/ukpga/2003/42/section/46
Peoe said when RIP was a bill that it was too strong and did not offer enough protection.
The poor quality of oversight of GCHQ is surprising.
[1] make here is a technical term and includes "make a copy of a digital file".
Well, I don't know about that. The fact that they're happily sending everything to the NSA can hardly be compatible with EU data protection law, and considering that their best friends, the US intelligence and law enforcement services, were caught red-handed doing illegal wiretaps right before the executive branch retroactively made it legal, well, it doesn't inspire much confidence. Now, if you start looking at, say, the activities of the British secret services during the Thatcher era, you come to realize that there may be a slight gap between the things they admit to do, and the stuff they actually do.
That said, wrt to Snowden being a traitor... if that is your reaction to "the previous and current administrations have created a completely out-of-control behemoth which invades both our and our allies' privacy without any oversight, and therefore threatens the notion of free and fair election anywhere in the western world", maybe you should rethink your priorities.