Somersetshire of Somerset County is the rural county in England where Willoughby's estate is located. The largest city in Somerset is Bath, which we know from Austen's other works. By 1801, Bath had become the ninth-largest town in England! Also, Solsbury Hill from the Peter Gabriel song "Solsbury Hill" is located in the county of Somerset!

Oxford University Press. A Dictionary of British History. Edited by John Cannon and Robert Crowcroft, Third edition., Third ed., Oxford University Press, 2015. . Accessed 14 Nov. 2020.

https://pointloma.on.worldcat.org/oclc/915595358 (specific article name and author's name?)