The British Monarchy is hereditary and not selected or checked by the electorate. They also have significant political power, in terms of access to government ministers and officials, as well as the ability to dissolve parliament.
The United Kingdom is a democracy. All people in it should have an equal say in how the country is run. The monarchy adversely affects the way we do politics. The institution of the monarchy and the Crown (not the royals themselves) give vast, almost unlimited powers to our politicians. This is a politicians' monarchy - it makes our government far too powerful and allows parliament to ignore the wishes of the people. The Royals get meetings with ministers, and writes letters to politicians which are taken seriously. Their opinion is listened to and can change the way the government acts on policies.This can either mean policies are worse, or not what the public wanted. For instance, focusing on building new aircraft carriers that were not necessary, or putting in restrictions on genetically modified foods. The Queen has significant power in that she has to invite the Prime Minister to form a government, and can reject them. She also has the power to dissolve parliament and call a general election. This is very undemocratic as it allows a single individual to wield huge amounts of power, rather than the people or their elected representatives 
Whilst the Royals could have influence, the training and education they receive makes sure they are highly responsible with it. If the Royals abused their power, then the government would take it away.
[P1] Democracy is valuable. [P2] The Monarchy impedes democracy. [P3] We should not support institutions that impede democracy.
Rejecting the premises