The UK election winner only becomes PM when King Charles III says so

The Labour Party has won Britain's general election, bringing a new party to power for the first time in 14 years. But Labour leader Keir Starmer won't actually become prime minister until a carefully choreographed ceremony on Friday during which King Charles III will formally ask him to form a new government.

It's a moment that embodies the fact that, technically at least, the right to govern in the United Kingdom is still derived from royal authority, centuries after real political power was transferred to elected members of Parliament.

The process is swift, if somewhat brutal for departing Prime Minister Rishi Sunak. Here's how the ceremonial events will unfold.

History meets the modern world

While Britain is a constitutional monarchy where the king's power is strictly limited by law and tradition, much of what happens here has echoes of the past. In this case, the process harkens back to a time when the king exercised supreme power and chose his preeminent minister the prime .