Progressive Conservative Party of Canada leadership elections
The first Progressive Conservative Party of Canada leadership election was held in 1927, when the party was called the Conservative Party. Prior to then the party's leader was chosen by the caucus or in several cases by the Governor General of Canada designating a Conservative MP or Senator to form a government after the retirement or death of an incumbent Conservative Prime Minister.
Source: Wikipedia — Progressive Conservative Party of Canada leadership elections (CC BY-SA 4.0)