Before the 17th century, the monarch had all three powers, the legislative, executive and judicial powers. The judiciary started gaining independence since the Case of Prohibitions 1607 and was fully independent after the Act of Settlement 1700, which effectively removed the power of the monarch to remove a judge at will. The independence of the legislature started with the Case of Proclamation 1611 and culminated in the Bill of Rights 1689, which curbed future arbitrary behaviour of the monarch and guaranteed Parliament’s power vis a vis the Crown. With these changes made to the UK constitution and as support grew for a democratic government, RP seemed out of place in the hands of the monarch and was slowly transferred into the hands of the government to be used in the name of the Crown.
It is possible for RP to be codified i.e incorporated into an AOP, as can be seen from the Constitutional Reform and Governance Act 2010 (CRGA). The CRGA codified several RPs, such as the RP to ratify treaties. The codification of RP meant that it would be under Parliamentary control and not the Executive. In the UK today, the UK government makes certain decisions based on the RP if they are not covered under any statutes. However, there have been several cases regarding the use of RP