Careful, the Conservative party may issue a fatwa er Papal edict against you. Someone needs to remind Baroness Warsi that she should be going to the head of the Church of England first not a foreign power that once demanded the death of one of the current Queens predecessors.
Women's suffrage? Legalisation of abortion and homosexuality?
Could go back to Henry 8th and the split from Rome...
I've avoided adding those. Certainly there's a good case that religious influence impeded social progress, but i'm looking at the institutional special treatment afforded to them and not other large clubs, and there have been plenty of atheist and secularist homophobes or misogynists.
You could add the repeal of http://en.wikipedia.org/wiki/Recusancy in 1650 (when it stopped being literally a crime not to go to the church of the government's choice every Sunday).