The 50th (Queens Own) Regiment of Foot was an infantry regiment of the British Army from 1755 to 1881.
The regiment was originally raised as the 52nd Regiment of Foot, but was renumbered in 1757 following the disbandment of the existing 50th and 51st regiments. In 1782, they changed their name to the 50th (West Kent) Regiment of Foot. In 1827 they were retitled 50th (Duke of Clarence's) Regiment of Foot, in honour of the future William IV of the United Kingdom, and then as the 50th (Queen's Own) Regiment of Foot in 1831 in honour of William's wife, Queen Adelaide. In 1881, they amalgamated with the 97th (Earl of Ulster's) Regiment of Foot to form The Queen's Own (Royal West Kent Regiment).
http://en.wikipedia.org/wiki/50th_(Queen's_Own)_Regiment_of_Foot
Images of the 50th Regiment of Foot during the New Zealand Wars