The rank was introduced throughout the British Army in 1871 to replace the rank of Ensign (Cornet in the cavalry), although it had long been used in the Royal Artillery, Royal Engineers and Fusilierregiments. At first the rank bore no distinct insignia. In 1902 a single star (sometimes referred to as a pip) was introduced; the ranks of Lieutenant and Captain had their number of stars increased by one to (respectively) two and three. The rank is also used by the Royal Marines.
In the Royal Air Force the comparable rank is Pilot Officer. The closest Royal Navy equivalent, Acting Sub Lieutenant, is actually junior, since it is not a full rank. New Zealand's navy - breaking with Royal Navy tradition - uses the Ensign grade for this rank equivalent.