Compared to medieval France and early Ireland, internet searching for Duceys in England is a welcome challenge, thanks to Britain’s deep recorded history even though early original records were written in Latin . As an example, partial records can be found for the then-small town of Walsall that go back before 1200 AD,. Early English history can be accessed through many e-books now in the public domain as well as a vast collection of on-line sources. These range from town and county historical collections, such as the Staffordshire and the Gloucestershire archives, to the online National Archives and British History Online. The site About.com Genealogy will give you their list of the 10 Top Databases for British Genealogy.
Family Search provides a list of some 390 records of Ducyes/Ducies/Duceys in their international genealogical index and a handful more in their Peerage, Baronetage, and Landed Gentry index. One must be careful in dealing with some individual records that deserve second-source confirmation.
Census & Electoral Rolls begin with the 1841 England Census and each proceeding version usually captures a handful of Ducies and Duceys.
While it is beyond the timeline of this project, a search of the 1911 Census for England and Wales shows:
33 male Ducies, either heads of households or single men;
19 female Ducies, which could be widows or daughters;
7 male Duceys, either heads of households or single men;
4 female Duceys.