This should be a case to watch. Not only will it test the UK terror law, but also the law of lawyer/client confidentiality. At the moment, the authorities, under UK law have blanket authority to get your password, not only if you are considered or suspected of being a terrorist, but because you are avoiding the law. The same law applies to constituent/ member of parliament confidentiality.
We have such tight laws here, that even an inquest can be held in secret if it is considered to be in the public interest in the war against terrorism. This is all about making the country safe and protecting the liberties of the state against the security of the individual.