Monarchy Myth Buster
The Queen certainly does have power, including the power to sign international treaties and deploy British troops abroad. It's true that most of these "royal prerogative powers" are today exercised by government, but that in itself is a serious problem.
You only have to look around to realise that Britain is no more unified than many republics – in fact, it's probably less so.
Our opposition to the monarchy isn't about money, it's about principles. If the monarchy cost nothing, we would still campaign for an elected head of state because hereditary public office has no place in a democracy.
It is true that most royals are “patrons” of a string of charities, but very often this is only on paper – their name may appear on the letterhead, but they are not an active ambassador for that cause.
The idea that the Queen can act as a check on politicians may be comforting, but it's a fantasy. The opposite is true - the monarchy gives huge power to politicians, while the Queen just does what she's told.