David Frost had sparred with Richard Nixon for hours, recording a series of interviews with the former president three years after he stepped down in disgrace over Watergate. But as the sessions drew to a close, Frost realised he still lacked something: an acknowledgement 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. Americans, he said, wanted to hear him own up to his misdeeds and acknowledge abusing the power of the White House.
"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, who died Saturday, it was the signature moment of an illustrious television career that spanned half a century and included interviews with a long list of the world's most powerful and famous, including virtually every British prime minister and US president of his time.
The lengthy interviews with Nixon were crucial for both men - Nixon was hoping to salvage his reputation for history, while Frost wanted to add another feather to his cap of famous interviews.
In the end, Frost wrung a mea culpa from Nixon over Watergate, the dirty tricks scandal which prompted his resignation in 1974 and left a lasting scar on the US political landscape.
"I let down my friends, I let down the country,'' the former president said.
Frost told BBC television in 2009: "We knew what we were trying to do ... and in the end his 'mea culpa' went further than even we had hoped.
"At the end of that I think we were aware that something sort of historic had happened and we'd gone further than expected.''
The encounter was turned into a play entitled Frost/Nixon, which was adapted into a 2008 film with Michael Sheen playing Frost and Frank Langella as Nixon. It was nominated for five Oscars.
Frost, 74, died of a heart attack Saturday night aboard the Queen Elizabeth cruise ship, where he was due to give a speech, his family said in a statement sent to the BBC.