Saying you have absolutely no oversight in the UK is not true. I recently read David Omand's "Securing the State" which is the most informative book I have found on how to integrate secret intelligence into a democratic society. Most of the analysis in the book focuses on the UK system as he is a longtime member of the UK intelligence community. There is a detailed discussion of how to meet the challenges of keeping a secret intelligence system accountable while maintaining its secrecy. Specifically see your JIC (Joint Intelligence Committee) and its history of post-portem analysis after notable incidents such as the Iraq WMD misread. That was about political influence into the workings of intelligence, scope overreach is of course the issue of the day but presumably they could take a crack at it.

In fact I have come to believe that your system is more well-managed than ours here in the US partially because it is a smaller country and hence easier to keep track of. See the Washington Post's article (before Snowden's revelations) on the mushrooming growth of myriad, largely redundant secret intelligence groups dispersed throughout various US agencies: http://projects.washingtonpost.com/top-secret-america/articl...