Thomas MaKay known as "Tam the Gun" fired the field gun every day at 13:00hr.
When the gun was fired, an observer at the Nelson Monument on Calton Hill,
would lower a ball that had been raised on a mast at the top of the monument.
This repeated the message that it was 13:00hr to the masters of ships in the port of Leith, and on the Firth of Forth,
and allowed them to set their chronometers to the correct time.

The new "District Gunner" is named Jamie Shannon and is known as "Shannon the Cannon".