A reader was surprised to learn that Theresa May has made David Davis ‘Secretary of State for Exiting the European Union.’ They thought it was odd that she could create a new department out of thin air. This is possible because of the constitutional metaphysics of the office of Secretary of State.
Although there are numerous individuals with the title of ‘Secretary of State,’ they technically hold the same office, and each one is theoretically free to act on behalf of the others (this is why Acts of Parliament refer to ‘the Secretary of State’ without qualification). While Davis will take office right away, the Queen will eventually formalize the creation of the new department by making an Order in Council under the Ministers of the Crown Act 1975. This Order will establish the new Secretary of State as a corporation sole and (if necessary) provide for the transfer of functions from other ministers. These Orders are subject to negative procedure (i.e., either House of Parliament can ask Her Majesty to annul them), but in practice, the Prime Minister will get their way. As a result, they have considerable latitude to shape their Cabinet.