Gordon Brown
I believe under Great Britain’s system of government, the House of Commons, and their elected Prime Minister, serves at behest of the Queen. It’s purely symbolic and a historical anachronism, degenerating into laws of pomp and circumstance. Nonetheless, the Queen could tell Gordon Brown to shove it, and perhaps if in a future epoch the Monarch decides to leverage its power under some nationalistic clings to Past Greatness, one will.