This compilation of essays is a whistle-stop tour through the entire history of modern British political life, from the days when elections were a show of hands, to the very recent Runcorn and Helsby victory of Reform by just six votes. Each of the eighty-eight essays are factual, deep in numbers and anecdotes, some more flow-y and chatty than others, and all rich in the context each by-election holds.
I was surprised that the mid-80s NI by-elections were omitted, though I guess trying to choose any to include or omit must have been hard. Still, this is a great compendium of political history told from a slightly different perspective than usual.
Sidebar: the appendices are taken wholesale from Wikipedia. I should know, because I created them.