One possibility is that the first part of the name was once the name of a stream which ran through the eponymous valley, perhaps one of a number of examples of Brittonic river-names corresponding to the Welsh word cyw 'young of an animal'.

He went on to co-found the Inland Waterways Association and the Talyllyn Railway Preservation Society, and to write many books on transport, engineering biography and industrial archaeology.

Penelope Chetwode, separated wife of Poet Laureate John Betjeman, mother of journalist and writer Candida Lycett Green and author of Two Middle-Aged Ladies in Andalucia, lived at New House, a cottage on Cusop Hill.

In the churchyard may be found the graves of the Methodist Martyr William Seward,[10][11][12] 'lawyer, author and yachtsman' Martin Beales, and Kitty (Katherine Mary) Armstrong (née Friend), victim of the notorious Hay Poisoner, a Commonwealth war grave of a Herefordshire Regiment soldier of World War I,[13] as well as a ring of ancient yew trees.

Cusop Dingle was home to the poisoner Herbert Rowse Armstrong, the only English solicitor ever hanged for murder, and the grave of his wife Katharine is in the parish churchyard.

In the upper reaches of Cusop is a notable geological horizon known as the Townsend Tuff Bed, which is a volcanic air-fall ash band.

He notes the quarrying and even an attempt to find coal in the side of Cusop Hill near 'The Criggy' circa 1800 by a tenant of Sir George Cornewalle.