Deputy prime minister

The office of Deputy Prime Minister is one that has only existed occasionally in the history of the United Kingdom. Unlike analogous offices in other nations, the Deputy Prime Minister does not have any of the powers of the Prime Minister in the latter's absence and there is no presumption that the Deputy Prime Minister will succeed the Prime Minister. The post has existed intermittently and there have been a number of disputed occasions as to whether or not the title has actually been conferred. More from wikipedia:

contributed by user Tom Loosemore