Each one of these three (Stoke, Desborough and Burnham) is a hundred; they are Stoke Hundred, Desborough Hundred and Burham Hundred.
The Stewardship of the Chiltern Hundreds is famously one of the two offices that MPs who wish to resign may apply to take. They involve no duties, but disqualify the incumbent from sitting as an MP, because they're "offices of profit under the Crown". The other office is the Stewardship of the Manor of Northstead (Northstead being in North Yorkshire).
© Haydn Thompson 2021