United Kingdom administrative law is a branch of UK public law concerned with the composition, procedures, powers, duties, rights and liabilities of public bodies that administer public policies. The general principle is that a public official, or an "administrator must act fairly, reasonably and according to the law. That is the essence and the rest is mainly machinery."
Ridge v Baldwin  AC 40, 72, Lord Reid, "We do not have a developed system of administrative law - perhaps because until fairly recently we did not need it".
Re Racal Communications Ltd  AC 374, 382, Lord Diplock, the creation of "a rational and comprehensive system of administrative law" was "the greatest achievement of the English courts" in his judicial career.