The Royal Family plays a largely symbolic role and most of their duties involve putting on social functions and entertaining esteemed guests. Also they are major tourist attraction. And they do hold some political power. For instance, the Queen must give royal assent to a bill before it passes and becomes the law. In that sense, the monarch has the power to veto proposed legislation similar to the President of the United States. Britain has its own Prime Minister, however, who holds a position that much more closely approximates the role the US President (as compared to the Queen).
Also, another reason they are such a big deal is that they “own” what is called The Crown Estate. It’s worth about £8.1 billion and 85% of the profits go to the treasury because of a deal King George III made in 1760. Originally the deal was that all the money went to the treasury and a fixed budget would be issued but in 2011 they made it a percentage. Each time a monarch ascends to the throne they make the same deal though it’s more of a formality.
The remaining 15% isn’t hers to spend, it’s used to maintain the palaces, pay for travel and generally facilitate them doing what they do.
It’s also worth noting that other countries like Canada also require royal assent for new legislation and this is provided by the Governor General who is appointed to represent the British Monarchy and to act on the Queen’s best interests (side note: the Queen is referred to as the ‘Queen of Canada’ when she visits Canada). This relationship is largely a symbolic gesture however, the Queen (or rather her Governor General representative) would be very unlikely to veto any Canadian bills and Canada would probably just declare full independence from Britain if the Queen ever tried to over-step her boundaries and actually exercise any political control over the country.
Canada has a queen. England also has a Queen. This person is the same individual but she holds 2 separate jobs, and 2 separate titles. The fact that the same individual always holds those jobs is not material.
When Canada’s Queen exercises her queenly powers she is not the “Queen of England”. When she exercises her Canadian Queen powers she acting as the Queen of Canada.
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