L.Col.David Watson was the son of Robert Watson of Muirhouse in Edinburgh. His father and grandfather were wealthy merchants and solicitors in the city. Muirhouse was an estate north of Edinburgh( Muirhouse Parkway), the house towers of which were finally demolished in the 1950s. During Cumberland's campaign Watson was depute quartermaster-general in the Board of Ordnance . Watson had a office in Edinburgh Castle which would have been Board property at the time. It seems likely that this area of the castle became the headquarters and drawing office of the Military Survey.