Francois Mitterand was a socialist, Konrad Adenaeur was a centralist.Actually the UK Tory provided the legal aspects to sort it out and establish it.
Over 750 delegates were present at the inaugural meeting.
Until about 1998 UK did not allow challenges to it's policies on HR bases. The only option was the ECHR.
The 1998 Act encompassed the ECHR into UK legislation.