The Crown is the permanent body in British Politics that, in theory, is the supreme power of the state. The Crown is the formal head of the executive, the legislative and the judiciary. All acts of state are done in the name of the Crown. In Britain, succession to the throne is determined by the 1701 Act of Settlement. Whereas a lot of what the Prime Minister can do is governed by conventions rather than legislation, the monarch is bound by statute to:not be a Roman Catholic or marry a Roman Catholic on the death of a monarch, the oldest male heir will succeed to the throne the death of monarch does not affect the holding of the office under the Crown as laid out in the Demise of the Crown Act of 1901. in the event of illness, a monarch may appoint Counsellors of State to exercise certain royal functions as laid out in the Regency Acts 1937-53.
By convention, the monarch will not refuse her assent to a Bill passed by Parliament and she will act on the advice of her ministers.
The Royal Prerogative:
"The Crown and British Politics". HistoryLearningSite.co.uk. 2005. Web.