Discuss the claim that the devolved structure of each part of the UK is immensely complicated, but that the overall constitutional arrangement of the UK is clear and straightforward.

The term 'devolution' is derived from the Latin 'to roll down'. It refers to the process in the United Kingdom of transferring power from the centre (Westminster) to the separate nations and regions. It involves a downward transfer of power from the supreme Westminster Parliament to a subordinate legislature. In McEldowney's words: Devolution provides various powers to the nations, as a form of self-government, but this does not create any entrenched autonomous powers because devolution maintains the sovereignty of the UK Parliament. It is important to be clear in distinguishing devolution, where powers are transferred but the UK Parliament does not relinquish any of its sovereignty, from a formal federal system. In the UK, the devolved governments have been created via statute and because of the doctrine of parliamentary sovereignty, devolution is, at least in theory, reversible. By contrast, under a federal system of government the constituent parts of the state enjoy autonomy and sovereignty.