The Conquest in Castles: Dating the Spread of Norman Castles across Britain, 1066 to 1199

How fast did the Norman castle frontier move after Hastings, and where did castles cluster? I assemble 3,288 castle sites of Norman type (castles, mottes, ringworks and keeps) in England, Wales and Scotland from Wikidata, deduplicated by item, and use only the dates Wikidata records. Just 317 sites (10%) carry any date and 113 fall between 1066 and 1199. The dated castles are a biased sample: 60% are Grade I listed against 6% of undated sites, and 15% are earthworks against 43%; but they are not biased by distance from the battlefield. Distance from Battle barely rises with date (Spearman 0.12 in England and Wales): by 1072 a dated castle stood 451 km away at Durham Castle. The frontier leapt rather than crept. I check the dates against the 41 castles named in the 1086 text of Domesday Book, which record 395 houses lost to castles in 9 towns. Domesday waste is regional, led by Cheshire, Shropshire, Herefordshire and Yorkshire, and places near castles show only a small excess of waste within their county (1.5 percentage points). Counting dated and undated sites together, a band 40 km either side of the England and Wales border holds castle sites at 3.2 times the density of the rest of the two countries. In Lancashire the first dated castle is of the 1090s, but Domesday shows a castle at Penwortham by 1086. Interactive version: https://tristan-hotham.github.io/norman-castles/. Data and code: https://github.com/Tristan-Hotham/norman-castles. Blog post: https://blog.tristanhotham.com/2026/10/27/norman-castles/.