I will use this definition taken from wikipedia:

"The monarchy of the United Kingdom, commonly referred to as the British monarchy, is the constitutional form of government by which a hereditary sovereign reigns as the head of state of the United Kingdom, the Crown Dependencies (the Bailiwick of Guernsey, the Bailiwick of Jersey and the Isle of Man) and the British Overseas Territories."

By 'last' I mean of this continuous succession of monarchs. If there's a period with no monarch then the monarchy is restored, I will count the last monarch before the interval as 'the last' for this market.

They must be named - 'future child of X' does not count.