In the absence of a comprehensive and reliable source, for party and factional alignments in this period, no attempt is made to define them in this article.
Where the cause of by-election is given as "resignation", this indicates that the incumbent was appointed on his own request to an "office of profit under the Crown".
Offices used, in this period, were the Stewards of the Chiltern Hundreds or the Manor of East Hendred and the Escheators of Munster or Ulster.
These appointments are made as a constitutional device for leaving the House of Commons, whose Members are not permitted to resign.
The c/u column denotes whether the by-election was a contested poll or an unopposed return.