GY postcode area

The GY postcode area, also known as Guernsey postcode area, its post town, is a group of 10 consecutive postal districts covering Guernsey, Alderney, Sark, Herm and the two inhabited lesser islets in that region of the Channel Islands. It was established in 1993 as an extension of the United Kingdom postcode system.
Coverage.
The approximate coverage of the postal districts. The post town is GUERNSEY for all postcode districts
In March 2009, Royal Mail had "agreed in principle" for the creation of the last district that would cover all addresses on the island of Alderney, to reduce confusion with those of smaller Sark to be left in GY9. The States of Alderney opposed that way round, and Sark changed from sector GY9 0 to acquire coding of GY10 1 on 5 January 2011.