Introduction to Constitutional monarchy and english monarchy

The constitutional monarchy is a form of monarchy.
The reigning sovereign has limited powers and established by a constitution, which are, however, many more than those you have in the parliamentary monarchy.
The legislative function is exercised by the sovereign and the government, the executive power is exercised by the sovereign and entrusted to the government, the latter is chosen by the monarch.

The English’s monarchy became constitutional when William of Orange signed the Bill of Rights in 1689, the most  important document of the material Constitution of the United Kingdom, which made England the first constitutional monarchy in Europe. With a tacit separation of powers between king (executive) and parliament (legislative).
The Monarchy is the oldest government institution in the United Kingdom.