With a regular reminder to the reigning monarch just outside the House of Commons in Westminster, a statue of Oliver Cromwell. Apart from the awful, awful acts that he commissioned against the people of Ireland, he also ensured that the concept of parliamentary supremacy against a sitting king that ignored or agitated against it, was demonstrated in a fairly direct way, the execution of King Charles I (there’s a statue of Charles I across the way, just to make sure you don’t miss the message)