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.
The House of Commons: 1754–1790 provides some guidance on the complex and shifting political relationships, but it is significant that the compilers of that work make no attempt to produce a definitive list of each member's allegiances.
Where the cause of the by-election is given as "resignation", this indicates that the incumbent was appointed at his own request to an "office of profit under the Crown".
These appointments are used as a constitutional device for leaving the House of Commons, whose Members are not permitted to resign.
In addition certain offices of profit, such as cabinet positions, required the MP to seek re-election.