Why is the UK still a member of the Council of Europe?

Why is the UK still a member of the Council of Europe?

Baku, Azerbaijan: A plain-clothes policeman detains an opposition activist demanding free speech during a rally Photograph: guardian.co.uk

The original question is

Why is Azerbaijan still a member of the Council of Europe?

The latest report on human rights violations in Azerbaijan raises serious questions about its ongoing membership of Europe's official human rights organisation

By the same token, given the UK's breach of the Convention and ignoring the Court decision on prisoners votes, shouldn't Afua Hirsch also be asking Why is the UK still a member of the Council of Europe?