Background: Recent research into cultural evolution has suggested that the distribution of many culturally neutral traits, including forenames, can be explained by a model of random copying, analogous to the process of random genetic drift. Aim: We test the proposition that in particular circumstances some forenames may not be neutral but, again by analogy with population genetics, may be subject to selection. Data sources and methods: The case study used to test this idea is the situation of Irish migrants and their descendants in late 19th century England and Wales. We compare forename frequencies among first- and second-generation Irish at the 1881 census of England and Wales, and show that in all counties studied the frequencies of the indicative Irish Catholic forenames Patrick and Bridget were much lower in the second-generation Irish, a result which applies consistently throughout 17 counties of England and Wales chosen for their substantial Irish-born populations. Conclusion: These results are explicable under a model of cultural evolution, informed by the historiography of Irish migration after the Great Famine, including the perception of derogatory Irish stereotypes exemplified by the sobriquets ‘Paddy’ and ‘Biddy’.