Documentary sources were consulted in order to find lists of surnames that were present in the medieval period. For the Wirral, these sources yielded 236 names compiled from the subsidy rolls from 1542, court proceedings from 1353, and ale-house licensing records from 1572. For West Lancashire a list of 269 surnames was obtained from a document listing those resident in Bickerstaffe, Burscough with Marton, Ormskirk, Scarisbrick with Hurlton, Skelmersdale, and Westhead with Lathom, who promised to contribute to the stipend of the priest of the altar of Our Lady at Ormskirk in 1366 and supplemented with surnames deriving from old local place names or place name elements. Thus the surnames themselves are not required to be Scandinavian in origin, though many of the surnames do contain Scandinavian elements from local place names from which the surnames were derived. It was necessary to convert some of the surnames to their modern equivalents to allow selection of study participants.
There were two sample sets from each location, each collected based on the two different criteria: ‘modern’ samples with no account taken of surname and ‘medieval’ men carrying a surname known have been in the region during the medieval period based on the old surnames lists. The sample sizes were as follows: Wirral modern (100 individuals) and medieval (37 individuals) and West Lancashire modern (49) and medieval (42) with men each bearing one of the surnames below.
Wirral: Barker, Beck, Bennett, Billing, Bird, Bryde, Bushell, Colley, Corfe, Edmunds, Forshaw, Gill, Green, Harding, Hesketh, Holmes, Hough, Joynson, Kemp, Kirk, Lunt, Oxton, Raby, Rathbone, Richardson, Rimmer, Robinson, Sampson, Scarisbrick, Sherlock, Skinner, Taskar, Tellett, Tottey, Upton, Young.
West Lancashire: Alker, Balshaw, Bilsborrow, Brown, Carr, Charnock, Coly, Cook, Cooper, Corfe, Crombleholme, Fletcher, Gill, Gray, Hesketh, Holland, Holmes, Hulme, Jones(son), Leyland, Lunt, Melling, Molyneux, Otty, Pendleton, Penketh, Pennington, Prescott, Rigby, Rimmer, Risley, Roby, Scarisbrick, Sephton, Serjeant, Swarbrick, Thomason, Walsh, Webster, Westhead.
In order to avoid bias, including two or more men with the same surname or spelling variant was avoided. Some surnames were found in both the Wirral and the West Lancashire sets but these were not thought to be related. Additional samples were collected from mid-Cheshire under the two generations of residence criterion given that it is close to the Wirral and West Lancashire but with a lower proportion of Scandinavian place name elements.