The London Regiment is a Territorial Army regiment in the British Army. It was first formed in 1908 in order to regiment the various Volunteer Force battalions in the newly formed County of London, each battalion having a distinctive uniform.
The London Regiment ceased to exist in 1938 with the battalions transferring to regular infantry regiments, the Royal Artillery and the Royal Engineers.
The London Regiment was reformed in 1992 through the regimentation of most of the remaining successors of the original regiment (except the Rifles and the Artists' Rifles).
More information on the Wikipedia page