Kept: 17 October
On 17 October 1956, Queen Elizabeth II switched on Calder Hall in Cumbria. It was the first full-scale nuclear power station in the world, and the papers said so plainly.
The same records say something else plainly too: Calder Hall's primary purpose was making weapons-grade plutonium for Britain's bomb programme. Electricity for the grid was the by-product.
It looked like a power station because that is what everyone called it. Both things were true on the same day, and nobody in the room was lying about either.
Kept line: the lights came on in the front of the house. The work in the back was something else, and everyone knew it.