People often ask why Coast Guard is written as two words in Ireland. Here's why:
Water Guard formed. Also known as the Preventative Boat Service. The Waterguard was the sea-based arm of revenue enforcement who patrolled the shore. The Waterguard was initially based in Watch Houses around the coast, and boat crews patrolled the coast each night. It was under Navy control from 1816 to 1822, when it and riding officers were amalgamated under the control of the Board of Customs.
15 Jan 1822
Coast Guard first established by Board of Customs. The Waterguard was absorbed into the Customs and Excise department in 1909.
Control of the Coast Guard passed to the Admiralty (Navy).
After Independence we changed over in Ireland to the Coast Life Saving Service. In the UK, the name "Waterguard" became misleading after 1923, when their domain was extended to the border between Northern Ireland and the Irish Free State.
UK Coast Guard placed under the Board of Trade, specifically dedicated to marine safety and life saving
UK Coastguard Act passed, formally defining its powers and responsibilities. Inadvertently believed to have used the single word version for the first time. Affected all crown dominions such as Canada, New Zealand etc. The duties formerly performed by Her Majestys Coastguard (HMCG) were taken over by Saorstát Eireann (Irish Free State) and the Coast Lifesaving Service (CLSS) was established as late as 1923.
It was later renamed the Coast and Cliff Rescue Service. In 1991 the service was renamed the Irish Marine Emergency Service, better known as IMES. In the year 2000, it became the Irish Coast Guard, which better denotes the service provided.
As we were not using the words Coast Guard it didn't affect us here in Ireland so that when we re-established the Coast Guard in 2000, it was re-established as the original two-word variant.