Has Your Surname Left Home? Birthplaces of Notable People by Surname in Great Britain, 1800 to 1899 and 1950 Onwards

British surnames are often tied to a region, but the open data needed to measure that for the whole population do not exist: the 1881 census with names is available only under a special licence, and modern name registers are not open. This note uses an open alternative and is explicit about its bias. From Wikidata I take 133,761 notable people born in Great Britain since 1700 who have a family name and a mapped birthplace, and compare where bearers of each surname were born in the nineteenth century (39,206 people) and from 1950 onwards (48,944). The sample is skewed: men are 86% of those born in the 1800s, and about one in four of them was born in London. For 349 surnames with at least 15 notable births in both periods, a size-adjusted dissimilarity index shows that regional clustering beyond chance fell by 48% at the median, from 13.7 to 7.1 percentage points, and 79% of surnames became less regional. Notable people with Welsh patronymic surnames were born in Wales 65% of the time in the 1800s and 35% since 1950. Tre-, Pol- and Pen- surnames were born in Cornwall about 9 times as often as notable people in general in the 1800s. Surnames that match a British place name were born within 25 km of a namesake 2.9 times as often as chance in the 1800s and 2.0 times since 1950. Against Scotland's registers, notable counts track the commonest surnames well (Spearman 0.85). The author's own surname, Hotham, has only 2 notable births, a reminder that the method is rich for common names and thin for most. Interactive version: https://maps.tristanhotham.com/surname-birthplaces/. Data and code: https://github.com/Tristan-Hotham/surname-birthplaces. Blog post: https://blog.tristanhotham.com/2026/10/29/surname-birthplaces/.