The borough consisted of originally of the town of Old Thirsk, and included a population of only 1,378 at the 1831 census. The right to vote was restricted to the holders of burgage tenements, of which there were 50 in 1831. The Frankland family were the local landowners (in 1816 Sir Thomas owned 49 of the 50 burgage tenements), and in effect could nominate whoever they wanted as Members of Parliament; there was no contested election in Thirsk between 1715 and 1832.
The Great Reform Act of 1832 expanded the boundaries to include the townships of Thirsk, Sowerby, Carlton Miniott, Sandhutton, Bagby and South Kilvington, increasing the population to 4,672 and encompassing 1,064 houses, which was considered big enough for the borough to retain one of its two members.
^In July 1849 a Commission of Lunacy declared Bell to be of unsound mind, but as the law then stood he could not be deprived of his seat on those grounds and remained an MP until his death in 1851
D. Brunton & D. H. Pennington, Members of the Long Parliament (London: George Allen & Unwin, 1954)
"Cobbett's Parliamentary history of England, from the Norman Conquest in 1066 to the year 1803" (London: Thomas Hansard, 1808) [1]
F W S Craig, "British Parliamentary Election Results 1832-1885" (2nd edition, Aldershot: Parliamentary Research Services, 1989)
J Holladay Philbin, "Parliamentary Representation 1832 - England and Wales" (New Haven: Yale University Press, 1965)
Henry Stooks Smith, "The Parliaments of England from 1715 to 1847" (2nd edition, edited by FWS Craig - Chichester: Parliamentary Reference Publications, 1973)
Frederic A Youngs, jr, "Guide to the Local Administrative Units of England, Vol II" (London: Royal Historical Society, 1991)
