It's not entirely by accident that the UK current ramp up of legalized government surveillance coincide with Brexit, as the UK doesn't actually have a democratic constitution limiting government surveillance outside of the ECHR treaty they signed as a prerequisite for joining the EU/EEC.
The UK signed the ECHR in 1950 (and were involved in writing it); the EEC did not exist until 1957.
The court http://www.coe.int/t/democracy/migration/bodies/echr_en.asp is what makes the ECHR significantly more effective then the unenforceable UN Declaration of Human Rights signed in 1948 only came into effect in 1859 and was only explicitly acknowledged as superior in British law with the still controversial Human rights act of 1998 https://www.supremecourt.uk/about/the-supreme-court-and-euro....
The fact that EU membership demand actual rather then pretend ECHR compliance is a fairly big deal in the anti-EU Tory circles currently running the show in the UK and some of them seem to presume that leaving the EU will absolve the UK of any duty to submit to the ECHR court http://www.telegraph.co.uk/news/2017/01/26/theresa-may-prepa... even though I am sure they think otherwise in Strasbourg.
but you are correct in stating that officially the ECHR came into dejura effect in 1950 under the Council of Europe where the UK unlike for the ECSC(1951) and the EEC(1957) was a founding member, but it's worth nothing here that the Council of Europe is a far more toothless organization(like the UN) then either the ECSC and the EEC.
Edit: fixed links
