No new prerogatives can come into existence. In BBC v Johns [1965] Ch 32, the BBC claimed that the Crown had a monopoly of broadcasting, exercised through the BBC, which was therefore entitled to Crown exemption from income tax. This contention was unsuccessful in the Court of Appeal. Lord Diplock stated: 'It is 350 years and a civil war too late for the Queen's courts to broaden the prerogative.' Thus, any prerogative power must originate from the powers possessed by the monarch before the advent of the modern parliamentary system, effectively 1688. But one should be aware of the way in which the courts can interpret the precise scope or reach of prerogative powers. See, for example, R v Secretary of State for the Home Department, ex parte Northumbria Police Authority [1988] 1 All ER 556.