Peter Russell mentioned in his summary of the King-Byng Affair of 1926 that the old custom that parliamentarians appointed to cabinet would resign their seats and run in a by-election complicated the 15th Parliament even more than the gubernatorial-prime ministerial constitutional stand off already had. I find this practice intriguing, and it’s no coincidence that it lapsed into obsolescence after the minority parliaments of the 1920s.
The prolific writer and constitutional scholar David E. Smith observed in The People’s House of Commons that “Until the 1930s, and extending back almost a century, by-elections in Canada were statutorily required when sitting members (in Ottawa, the provinces, or the colonies before that) were appointed to cabinet.”
My random trawling of YouTube for material on Westminster parliamentarism led me to a excerpt of Douglas Carswell, Conservative MP for Clacton in the British Parliament. Carswell argued that parliament used to provide a more effective check on cabinet in the 19th century and early 20th century as compared to today, and cited this same tradition that MPs appointed to cabinet would resign their seats and run in by-elections as evidence. Apparently this practice ceased to be in the early 20th century in the UK.
Some Canadian constitutional scholars (David Smith, Jennifer Smith, Peter Russell, etc.) argue that the injection of populism into the Westminster system (what David Smith calls “electoral democracy”) would irrevocably alter the Crown-in-Parliament and threaten the viability of responsible government itself. However, I content that this old tradition of running in a by-election upon appointment to cabinet within the life of a parliament shows that popular of approval of the executive complemented the confidence convention in the parliamentarism of the 19th century. Parliamentarism did not come about by design, but by evolution, sometimes accidental and peaceful, and sometimes violent. Surely a system that has existed for at least 800 years can better accommodate popular sovereignty in the 21st century, given this precedent from the 19th.
 David E. Smith, The People’s House of Commons: Theories of Democracy in Contention (Toronto: UofT Press, 2007): 5.