Metrication in the United Kingdom that reported in 1818, and again in Parliament by Sir John Wrottesley in 1824. Another Royal Commission was set up 1838 by Chancellor of the Exchequer Thomas Spring Rice and it reported in 1841 that decimal coinage was required first. A third commission in 1853 advocated decimal coinage in the form £1 : 10 florins : 100 cents: 1000 mils. The first florins (one tenth of a pound sterling) were struck in 1849 as silver coins weighing and having a diameter of . An early supporter of the "Decimal Association" was the mathematician Augustus de Morgan whose articles supporting the
Guernsey pound than the modern version and the diameter also measured slightly less. The 1-pound coin ceased to be legal tender on 15 October 2017 to coincide with the withdrawal of the circular £1 coin in the UK. The UK's new twelve-sided £1 coin will be the only £1 coin that is legal tender on the island. The first decimal issues continued with the same obverse as the last pre-decimal issues until 1985, when Raphael Maklouf's portrait of Queen Elizabeth II was added. Ian Rank-Broadley's portrait of the Queen has appeared since 1998. Designs on the reverses of Guernsey's decimal coins are: