‘Lost’ David Frost interviews with Paul McCartney and others set to air on Radio 4

David Frost will long be remembered as the broadcaster who went head to head with former US president Richard Nixon in a series of interviews following the Watergate scandal.

But a trove of previously lost recordings of Frost’s interviews, with some of the greatest entertainers of the last 70 years, will now be brought back to life for a new radio series.

His son, Wilfred Frost – who followed in his father’s footsteps as a journalist – has spent the last five years searching and digitising his archives.

“There’s tapes that were lost for a generation,” he told The Telegraph.

He said he felt a “duty” to “celebrate” his father’s legacy and has produced a nine-part series, which will air on BBC Radio 4. A television show is also expected to follow next year.

To gather the lost recordings, he had to strike a deal with the US broadcaster CBS for the rights to some interview tapes that had been stored in its archives in Pennsylvania.

His father produced a show five nights a week between 1968 and 1972 with the broadcaster, with 90-minute, longform interviews, which only ever aired in the US once, and never in the UK.

The tapes “sat gathering dust since then, because CBS, I think, sort of overlooked the value of what was in there”, he said.

Elsewhere, he found tapes stored in Cleveland, Ohio, that the family didn’t even know existed.

“Dad had storage in New Jersey, in London, and two in LA, so there was a lot to go through,” he said.

The broadcaster spent years going through his father’s archives and made other “amazing discoveries” along the way, including some of his old work contracts that stipulated he worked for “50 weeks a year, he had two weeks off only”.

The formidable interviewer would brag about “inventing the eight-day week” in the late 1960s and early 1970s, his son explained.

“He did the David Frost show five nights a week, but they recorded the Friday show on Thursday. He’d fly back, and then he did Frost on Friday, Saturday, and Sunday for London Weekend Television, in London,” he said.

“So he literally did eight shows a week, commuting between London and New York, pre-Concorde.”

“I just don’t quite know how he managed it,” he added.

Each episode will track the life story of a high-profile interviewee David Frost had an “enduring relationship” with across the decades, such as Elton John, Muhammad Ali and Paul McCartney.

“While this is the entertainers and it’s fun, there is a lot of depth to it too; Elton John talking about his addictions both when he was still an addict and then after he was an addict – because dad was the person he spoke to about that on both occasions,” he said.

In the episodes with Elton John and Andrew Lloyd Webber, listeners will hear the artists at their own grand pianos in their homes “explaining how they wrote certain songs in a way … that is really unheard of”, he added.

The Frost Tapes: The Entertainers begins on August 8 on Radio 4 and BBC Sounds, and will include episodes on Sammy Davis Jr, Muhammad Ali, Michael Caine and Elizabeth Taylor.

A ninth episode with Lauren Bacall will drop on BBC Sounds at the same time.

“It never ceases to amaze me how brilliant he was at what he did – regularly and repeatedly getting the most famous people in the world to open up as if they were in the privacy of a confessional booth,” Mr Frost said.

“As it happens, many of these conversations have been private for too long – I am delighted to share them with the world once again.”