The 42nd Regiment was raised in 1739 as the 43rd. In 1749 it became the 42nd. It received the title of ‘Royal Highland Regiment’ in 1758 and in 1795 was permitted to wear a red feather as a special distinction.

The 73rd Regiment was raised in 1781 as the 2nd Battalion of the 42nd. It was numbered as the 73rd Regiment in 1786 and entitled ‘The Perthshire Regiment’ in 1863.

The 42nd and 73rd Regiments were amalgamated in 1881.