Giles Martin likes to believe that John Lennon wrote "Now and Then," the recently released final Beatles song, as a sweet testament to his bandmates.

"Maybe that's because it makes me happy to think that," Martin says with a pensive smile.

Peter Jackson, the film director who steered the band's 2021 documentary "Get Back" and was instrumental in resurrecting "Now and Then," has a slightly different take, according to Martin.

"Peter is convinced it's a love letter to Paul (McCartney). Paul truly loved John and without question they missed each other. There were only four Beatles and like trauma, they were the only ones who could understand (what that was like) because they're the only ones who experienced it. I think that’s why Paul wanted to finish 'Now and Then.' It was seen as the final collaboration of the four of them."

'The Lyrics':Paul McCartney has 'a thing for older ladies,' more revelations in paperback

The song, which arrived last week and is part of the newly remastered "The Beatles 1967-1970" (aka "The Blue Album") released Friday along with "The Beatles 1962-66" (aka "The Red Album"), was co-produced by Martin and McCartney.

In addition to the sanitized audio, which originated on a Lennon demo tape from the late-'70s, the song features guitar from the late George Harrison, bass and drum additions from Ringo Starr and McCartney and a new overlay of strings written by Martin, McCartney and composer Ben Foster.

Martin, 54, the son of legendary Beatles producer George Martin and a longtime audio guru for the band, shared some other insights about "Now and Then."

How AI is used in the Beatles' 'Now and Then'

McCartney set off a firestorm among fans when he mentioned in a June interview with the BBC that artificial intelligence was used in the creation of "Now and Then." The initial thought was that the remaining Beatles utilized AI to create Lennon's vocals.

But further clarification revealed that the audio technology Jackson employed to clean up the audio during the construction of the "Get Back" documentary was what was used to spruce up Lennon's old demo tape. All of the music and vocals are original.

Martin jokes that he's glad McCartney was the one who announced the existence of the song this summer – "If anyone is going to leak a song, let it be Paul McCartney!" – and understands why people might be confused.

"It DOES involve AI, but not how people think it does. It's non-generative, purely archeological. We're just using machine learning to separate John's voice (from the instrumentation). What we're hearing is what he was singing in the room. Someone asked in an interview, 'Did you use AI to make Paul and Ringo sound younger?' It's like, have you heard the song?!"

Giles Martin wishes his father and John Lennon were still alive

Martin and McCartney worked on the swooping string element of "Now and Then" a year ago and McCartney oversaw the recording at Capitol Studios – a familiar Beatles haunt – in Los Angeles.

When asked what feeling he was going for in composing the strings, Martin pauses.

"I suppose I tried to rip off my dad, to be honest, because he should be doing it," Martin says of his esteemed father, who died in 2016. "John should be in the room and my dad should be doing the string arrangement."

Martin, who oversaw the lauded reconstruction of the Beatles' catalog for "Love," their Cirque du Soleil show and soundtrack, often refers to his father’s work with the band with keening reverence.

"I know that Paul misses my dad and he misses what my dad would be able to do for him creatively. He's worked with other string arrangers – some brilliant – but never had quite the same synergy as he had with my father. Nor probably do I, I might get closer in a way because there a genetic connection. I don't want it to sound too 'Game of Thrones,' but that sort of thing does exist."

Are there any other Beatles songs in the vaults?

Though McCartney and Starr have repeatedly said "Now and Then" is the final Beatles recording, Jackson has hinted in interviews that the might still be more gems in the vaults.

That's possible, Martin says, but with one major difference: Nothing else includes all four of the Beatles playing.

"I'm sure there are some demos that are available, but it wouldn’t have all four of them on it. The key is that ('Now and Then') came from those sessions in 1995 where George is playing and he won’t be playing on anything else."

As for the oft-referenced "Carnival of Light," a 15-minute avant-garde instrumental track that has never been officially released, Martin is skeptical about its future.

"I've heard it and I don’t see it ever being a song. It may have its place in a different setting, like an installation or an event," Martin says. "But I think with any of their music and getting your hands on it, it depends what it is."

More:John Lennon's ex May Pang says he 'really wanted' to write songs with Paul McCartney again