On a warm cloudless night during the last week of the program, she persuaded him to sneak away to a garden on a hill, where they sat talking for hours and sharing intimate secrets.

But they didn’t kiss. “I’m not sure I would have known how — I was a very young 16,” said Mr. Abella, a lawyer who was until last September a counsel to a municipal investigative commission in Toronto, and whose mother, Justice Rosalie Silberman Abella, sits on the Supreme Court of Canada. The next day in class they were embarrassed by the encounter, as teenagers can be, and pretended they hadn’t talked.

“He would look up and see me, and I would look down,” she said.

Two days later they were at Heathrow Airport for their return home. It was all coming down to their final goodbye. But while he was in a washroom preparing something to say, she boarded her plane. He had no contact information for her, and a big problem: he was infatuated.

So was she. On the anniversary of their meeting, she tracked down his number in Toronto and left a message.

About to return to Oxford, he looked forward to calling her back during a long layover in Newark. But he couldn’t find her number. “I wandered around Newark airport for five hours looking for a Manhattan phone book,” he said.