These twin locks were built in the 1790s for movement of industrial goods, but today form an attractive feature in the quiet rural landscape.
Locks were needed at Carreghofa because the Montgomery Canal descended from the higher ground at Llanymynech to the broad valley floor, where it crossed the river Vyrnwy on an aqueduct. Each lock was long enough to hold one “narrow boat” (the name for a canal boat). With the gates at each end closed, the water was drained from the lock until the boat had descended to the lower canal level, when the bottom gate was opened for exit.
Boats travelling towards Llanymynech were lifted in the locks. Each cycle of lowering and raising consumed water. A feeder channel c.2km in length was dug from a weir on the Tanat river at Carreghofa Hall, north of here. Just beyond the eastern lock you can still see a broad area of water at the junction of the “Tanat Feeder” and canal.
The houses beside the canal here were built as accommodation for the lock keeper and toll collector. The canal company levied a charge on passing boats.
Carreghofa was the meeting point of two canals, promoted and constructed separately but with the aim of linking together. First the Ellesmere Canal was built from Shropshire to Carreghofa, mainly to support the Llanymynech limestone industry. The Montgomeryshire Canal (as it was then known) joined up at Carreghofa in 1797. From 1836 passengers could travel from Newtown to London by a boat service which had priority over other narrow boats.
Contrary to some speculation, the name Carreghofa has nothing to do with King Offa. Early forms of the name referred to a castle erected c.1100 by Robert de Bellême, Earl of Shrwesbury, where Carreghofa Hall now stands. Carreg = rock. Hofa is a variant of Hwfa, a personal name that was once common.
With thanks to Professor Hywel Wyn Owen of the Welsh Place-Name Society