One o’ Clock.

Yes, as they say in Edinburgh if you see someone jump when the One o’ Clock gun goes off their tourist’s.
This is Nelsons Monument on top of Calton Hill & the ball drops at one o’clock when gun goes off at the Castle. It was to sign to ships on the Forth so that the could set their chronometers.
https://www.edinburghmuseums.org.uk/venue/nelson-monument