The British Forces Post Office (BFPO) provides a postal service to HM Forces separate from that provided by Royal Mail in the United Kingdom. BFPO addresses are used for the delivery of mail in the UK and around the world.

Alderney is the northernmost of the inhabited Channel Islands. It is part of the Bailiwick of Guernsey, a British Crown dependency. It is 3 miles (5 km) long and 1+1⁄2 miles (2.4 km) wide.

Guernsey is the second-largest island in the Channel Islands, located 27 miles (43 km) west of the Cotentin Peninsula, Normandy. It is the largest island in the Bailiwick of Guernsey, which includes five other inhabited islands (Alderney, Herm, Jethou, Lihou, and Sark) and many small islets and rocks. The Bailiwick has a population of 63,950, the vast majority of whom live on Guernsey, and the island has a land area of 24 square miles (62 km2).

The Isle of Man (Manx: Mannin , also Ellan Vannin or Mann ), is a self-governing British Crown Dependency in the Irish Sea, between Great Britain and Ireland. It is recognised as one of the Celtic nations and is the homeland of the Manx people, a Celtic ethnic group. As head of state, Charles III holds the title Lord of Mann and is represented by a Lieutenant Governor. The government of the United Kingdom is responsible for the isle's military defence and represents it abroad

Jersey , officially known as the Bailiwick of Jersey, is an island country and self-governing British Crown Dependency near the coast of north-west France. It is the largest of the Channel Islands and is 14 miles (23 km) from the Cotentin Peninsula in Normandy. The Bailiwick consists of the main island of Jersey and some surrounding uninhabited islands and rocks including Les Dirouilles, Les Écréhous, Les Minquiers, and Les Pierres de Lecq.

Ireland ( Irish: Éire Ulster-Scots: Airlann ) is an island in the North Atlantic Ocean, in north-western Europe. It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel. Ireland is the second-largest island of the British Isles, the third-largest in Europe, and the twentieth-largest in the world.Geopolitically, the island is divided between the Republic of Ireland (officially named Ireland), an independent state covering five-sixths of the island, and Northern Ireland, which is part of the United Kingdom.