County of south‐west Wales. The county was created at the Act of Union with England in 1536. The peninsula, part of the Welsh kingdom of Deheubarth, was conquered by Arnulf de Montgomery c.1090, who established the lordship of Pembroke in the south. Henry I reinforced the occupation of the south by promoting a Flemish immigration. The result was that the county had a distinctive dual character, markedly English to the south, Welsh to the north. In 1974 the county became part of Dyfed, but was reconstituted in 1996 as a unitary authority.
Pembrokeshire has been pre‐eminently an agricultural county, the southern section being one of the few areas of arable land in Wales, its mild maritime climate giving rise to early vegetable‐ and flower‐growing. The whole coast is designated a heritage coast and makes up the Pembrokeshire National Park. The coast is broken by the major sea inlet (ria) of Milford Haven. Once a major fishing port, it is now dominated by oil refineries, developed for supertankers.