Montgomeryshire (Sir refaldwyn). Border county of mid-Wales. It was created at the Act of Union with England in 1536 and was coincident with the Welsh kingdom of southern Powys. Powys, which covered much of mid- and north-east Wales, was split at the end of the 12th cent. and the south (Powys Wenwynwyn), separated from the north (Powys Fadog), was the basis for the county in the form of the Norman lordship of Powys, together with the crown lordships of Montgomery, Cydewain, Ceri, and Caus. The English name comes from the French home of the early conqueror, Roger de Montgomery.

Montgomeryshire comprises the eastern sloping plateaux of the Cambrian mountains, broken by a series of valley lowlands along the river systems of the river Severn and its tributaries, the Banwy, Vyrnwy, and Clywedog. However, it extends across the mountain massif to include part of the western flowing Dyfi drainage. The deeper upper parts of the valley systems have been used to create reservoirs for water supply for north-west England, notably Lake Vyrnwy (1880–90) for Manchester. The more recent Llyn Clywedog (1968) is a regulator of river flow for downstream extraction. There was an early woollen industry in the towns of the Severn valley, and its demise, together with the closure of lead-mines and greater capitalization of agriculture, led to extensive depopulation. In response, Newtown was developed from 1967 under the New Towns Act and has a range of light industry.

Montgomery is pre-eminently border terrain; every aspect registers an east to west transition whether it be landscape, farming, or culture. Welsh is spoken by 23.3 per cent of the population but characteristically ranges from 4.6 per cent at Church Stoke on the border to 68.3 per cent at Llanbrynmair in the extreme west. In 1974 Montgomeryshire became a district in the county of Powys and was incorporated in the unitary authority of Powys in 1996. The population in 1991 was 51,527.

Harold Carter