The £1 coin in base metal (as opposed to the gold sovereign, which has a nominal face value of one pound too), nickel-brass was introduced in 1983, as a replacement for the £1 banknote. The reverse design of the first £1 coin showed a depiction of the Royal Coat of Arms, representing the United Kingdom as a whole and was issued until 2008 with no change, then with a re-design in 2015, in rotation with other designs representing England, Scotland, Wales and Northern Ireland, alternating each year. Before 2008, the Royal Mint only issued one design per year, but starting in 2008 it sometimes had more types during the same year.
In 2008 the common UK reverse was changed to this new design by Matthew Dent. In a world-first concept, and in a re-design of all circulating denominations, the designs for the 1p, 2p, 5p, 10p, 20p and 50p coins were changed to depict sections of the Royal Shield that form the whole shield when placed together. The shield in its entirety is featured on the £1 coin.
The coin is made of Nickel-Brass, with composition of 70% copper, 5.5% nickel and 24.5% zinc.
This type of one pound was issued every year until 2016. The coins circulated until 2017, when they were demonetised and replaced with the current 12-sided bimetallic one pound coin.
The reverse features the Shield of the Royal Arms of the United Kingdom (and not the whole Royal Arms, as the earlier design). The Shield is divided into four parts; England is represented by the three lions passant guardant (walking to left, looking at the observer) in the first and fourth quarters, Scotland by the lion rampant in the second and Northern Ireland by the harp of Ireland in the third.
The value and denomination, ONE POUND, are around left and right, divided by the Shield.