It was an original constituency represented in Parliament when the Union of Great Britain and Ireland took effect on 1 January 1801, and returned one Member of Parliament (MP), elected by the first past the post system of election.
"[1] Parliament therefore passed the Sligo and Cashel Disfranchisement Act 1870[2] (33 & 34 Vict.
In 1881 the county's MP, Thomas Sexton, introduced a private member's bill to re-enfranchise the borough, which was defeated on second reading.
On petition, Towneley was unseated on 6 June 1853 due to bribery by his agents, causing a by-election.
Knox's election was declared void on 2 March 1869, and no writ was issued to find a replacement MP.