The nod likely goes to John Diefenbaker who met Sir Wilfrid Laurier, while peddling newspapers as a university student in Saskatoon. Arthur Meighen was his party leader when he first became an MP; William Lyon Mackenzie King sat on the benches across the aisle, as did Louis St. Laurent, Lester Pearson, John Turner, Jean Chretien and Pierre Trudeau later on. On a dare, law student Brian Mulroney talked him into speaking to his class. Diefenbaker died while his colleague Joe Clark was PM. That’s 10 in all, but it’s probable he also met R.B. Bennett and Paul Martin, and possibly Sir Robert Borden, Kim Campbell — and maybe even Stephen Harper.
Laurier served in the cabinet of Alexander Mackenzie, and sat across the House from Sir John A. Macdonald, Sir John Abbott, Sir Mackenzie Bowell, Sir Charles Tupper, Sir John Thompson, Borden, Meighen and Bennett. King was a member of his cabinet. And, of course, there was that newapaper he bought from Diefenbaker. That’s 11 PMs — ahead of Diefenbaker. But the only addition to Laurier’s list is a possible encounter with St. Laurent.
Don’t forget Turner saved Diefenbaker from drowning in Barbados.
This was truly the most interesting meeting of a sitting and future Prime Minister. Not surprisingly, the two became rather good friends after the incident.