The UK had at least one superbly "uncharismatic" Prime Minister in living memory: Clement Attlee. Even though he was Labour, Thatcher wrote of him:
"Of Clement Attlee, however, I was an admirer. He was a serious man and a patriot. Quite contrary to the general tendency of politicians in the 1990s, he was all substance and no show"
https://en.wikipedia.org/wiki/Clement_Attlee