The Conservatives lost two seats in 2022, two in 2021, and none in 2020.

The question is about losses, not net losses (so it doesn't matter if the Conservatives gain seats in other by-elections).

These must be by-elections to the U.K. House of Commons, not any other body.

Losses are counted relative to the last election in the seat (eg if a Conservative MP defects to another party, calls a by-election and wins, like in Clacton in 2014, this counts as a loss).

The same constituency can be counted as a loss more than once (though this would require three by-elections in the seat in one year).

See here for a list of recent by-elections: https://en.wikipedia.org/wiki/List_of_United_Kingdom_by-elections_(2010%E2%80%93present)