David Frost

LONDON — David Frost, best known for his compelling interviews of former President Richard Nixon, died of a heart attack Saturday night aboard the Queen Elizabeth cruise ship, where he was due to give a speech. He was 74.

Frost interviewed the former president three years after he stepped down in disgrace over Watergate. As the sessions drew to a close, Frost realized he still lacked something: an acknowledgment by Nixon that he had been wrong.

Nixon had admitted making mistakes, but Frost put down his clipboard and pressed his subject on whether that was enough.

“Unless you say it, you’re going to be haunted for the rest of your life,” the British broadcaster told Nixon.

What came next were some of the most extraordinary comments ever made by a politician on television. For Frost, it was the signature moment of an illustrious television career spanning half a century.