Leaders the world over are sharing their fondest memories of Margaret Thatcher, but it’s likely the former British prime minister only called one “a naughty schoolboy,” and that was the late Pierre Elliott Trudeau.

Thatcher, Britain’s first female prime minister, died Monday after suffering a stroke. She was 87.

After word of Thatcher’s death spread to Canada, current and former politicians paid tribute to the woman who led Britain from 1979 to 1990. But two former prime ministers, Trudeau and Brian Mulroney, were in office through the key years of her time in power, and had very different relationships with the woman known as the Iron Lady.

On Monday, Mulroney fondly remembered Thatcher for turning Britain, “the sick man of Europe,” into an economic power and for serving as a bold leader during major world events, such as the collapse of the Soviet Union.

But Mulroney recalled that the two had “a running series of skirmishes … including some pretty bruising battles” over their differences of opinion on the apartheid regime in South Africa.

Thatcher, he said, tried many times to change the opinion he was articulating on behalf of the Commonwealth, which “favoured comprehensive sanctions against the apartheid regime in South Africa, and the liberation of Mandela and the recognition of the ANC (African National Congress).”

However, Mulroney said, Thatcher’s opposition to his views, particularly on sanctions, was more nuanced than her opposition might suggest.

“She was opposed not to a better life for South Africans, she was very much in favour of that, but she didn’t believe in sanctions because she felt that they penalized black South Africans more than anybody else,” Mulroney recalled during an interview with CTV’s Power Play.

Despite those differences of opinion, Mulroney said Thatcher’s economic policies inspired his government’s privatization and deregulation drive. She also was a strong supporter of the North American Free Trade Agreement he negotiated with U.S. president Ronald Reagan.

But he also recalled that, “apart from being a superb and strong leader, she was also in private a very charming and polite and respectful and enjoyable friend.”

The Mulroney, Thatcher and Reagan families often vacationed together after the three leaders left office, including numerous visits to Southampton.

There, Mulroney recalled one particular night when, “after a couple of whiskies,” Thatcher sang “The White Cliffs of Dover.”

“Listening to her slightly elevated contralto singing that, it was very moving because she was a living part of British history at the time,” Mulroney said. “I saw a very human side of Margaret Thatcher.”

In contrast, if Trudeau were alive, he would have some different tales to tell of Thatcher, including the time she scolded him at a G7 meeting in Montebello, Que. in July of 1981.

The book “Ronald Reagan and Margaret Thatcher: A Political Marriage,” by Nicholas Wapshott recounts that “there were a number of sharp clashes between Thatcher, backed by Reagan, and Trudeau, given moral support by (French president Francois) Mitterand.”

At one point, Reagan recalled, Thatcher said to Trudeau: “Pierre, you’re being obnoxious. Stop acting like a naughty schoolboy.” Reagan went on: “I thought at one point Margaret was going to order Pierre to go stand in a corner.”

According to the book, Trudeau’s “outbursts” against the U.S. and British leaders “were to prove a regular item at the G7 meetings.”