The King's Shropshire Light Infantry (KSLI) was a light infantry regiment of the British Army, formed in the Childers Reforms of 1881, but with antecedents dating back to 1755. It served in the Second Boer War, World War I, World War II and Korean War. In 1968, the four regiments of the Light Infantry Brigade amalgamated to form The Light Infantry, with the 1st KSLI being redesignated as the 3rd Battalion of the new regiment.

The Somerset and Cornwall Light Infantry (SCLI) was a light infantry regiment of the British Army. It was formed in October 1959 by the merger of the Somerset Light Infantry and the Duke of Cornwall's Light Infantry, and was itself merged with three other regiments of the Light Infantry Brigade in 1968 to form The Light Infantry.