How democratically accountable are the UK’s security and intelligence services?

As part of the 2017 Audit of UK Democracy, Sean Kippin and the DA team assess the ways in which the UK’s four main security services are scrutinised, to ensure that they are operating legally and in the public interest. For matters that must be kept secret, ‘compromise’ forms of scrutiny have now been developed in Parliament. But how effectively or independently do they work?