[3] A by-election was held in Grendon Underwood and Brill on 23 December 2015 after the death of Conservative councillor and former leader of the council John Cartwright.
[4] The seat was held for the Conservatives by Cameron Branston with a majority of 51 votes over Liberal Democrat Julian Newman.
[4] A by-election was held in Elmhurst on 6 April 2017 after the resignation of UK Independence Party councillor Andy Hetherington.
[8] A by-election was held in Wendover and Halton on 4 May 2017 after the resignation of Conservative councillor Andrew Southam.
[11] A by-election was held in Central & Walton on 22 March 2018 following the resignation in February of Conservative councillor Edward Sims.