In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Llanddyfnan like this:
LLANDDYFNAN, a parish, with a village, in the district and county of Anglesey; near the river Cefni, and down to Red Wharf bay, 2 miles W of Pentraeth, 6½ W by N of Beaumaris, and 6¼ NNW of Menai-Bridge r. station. Post town, Pentraeth, under Menai-Bridge, Anglesey. Acres, 3,506; of which 25 are water. Real property, £2,664. Pop., 720. Houses, 168. The property is divided among a few. Llanddyfnan Place is a chief residence. Some common lands were enclosed between 1851 and 1861. Limestone abounds and is worked. Traces exist of a Roman road; and a large maenhir is near the church. The living is a rectory, united with the p. curacy of Llanfair-Mathafarn-Eithaf, in the diocese of Bangor. Valne, £280. Patron, the Bishop of Bangor. The church is dedicated to St. Dyvnan, and was rebuilt in 1847.
A Vision of Britain through Time includes a large library of local statistics for administrative units. For the best overall sense of how the area containing Llanddyfnan has changed, please see our redistricted information for the modern district of the Isle of Anglesey. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Llanddyfnan and units named after it.
GB Historical GIS / University of Portsmouth, History of Llanddyfnan in The the Isle of Anglesey | Map and description, A Vision of Britain through Time.
Date accessed: 24th July 2016
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Llanddyfnan".