Lancaster is a British surname. It comes from the name of the city Lancaster in northwestern England, or alternatively from the county which was also named after it, now more commonly known as Lancashire. Lancashire was once a variant surname of Lancaster, although the two surnames are now considered separate.
1. The E-L143 cluster of Lancaster families who have been traced back to the areas around the Lancashire and Yorkshire towns of Gisburn, Colne, and Cliviger (near Burnley). (E-L143 is one of the branches of E-V13. So far it seems to be isolated to surnames from northwestern England.)
The core of the cluster appears to be the families who lived since Tudor times in Gisburn, which was historically part of the West Riding of Yorkshire, on the border with Lancashire.
However, the Cliviger family is listed in Burkes Peerage as a family that can be traced back to Askham in Westmorland. Some of the project's genealogists have questioned the details of this pedigree.
A Westmorland connection would however be a logical, partly because of the high number of Lancasters who lived there, and the closeness, but also partly because of the close match which this Lancaster lineage has with most families having surnames based upon the hamlet name Satterthwaite. See Satterthwaite.
The cluster containing these Lancasters, Satterthwaites, Satterfields, etc also contains people with the surname Pepper, Holmes and Pursifull.
2. An unusual E-M78* individual, whose paternal ancestry is in Cumbria in northwestern Britain.