History of vote buying

These stories about vote-buying in the Conservative Party leadership race -- the O'Leary team that accused the Bernier tearm now being accused itself -- must be the oldest of old news.  It's a vote-buying contest, ain't it?  The candidate whose team buys the most "memberships" (ie, votes) gets to pick the winner.  That's the way all mass-party leadership races work  It's the way they are supposed to work.

Complaints that some team has bought too many votes ...?  Doesn't that just mean they are going to win? And once they have the leadership, who would be able to sanction them for ... winning?

Historical question: given that no leadership race has been free of these allegations, has any leadership race winner ever been sanctioned for committing or condoning irregularities in the accumulation of memberships?