BACK in the 1960s, the Cumbrian writer Hunter Davies was just as much a fan of The Beatles as millions of other young people - but he confesses to finding the lyrics of their early songs rather simple, even banal.

That was until he experienced the enigmatic poetry and ethereal orchestration of Eleanor Rigby.

It was as if the most popular pop group of the era had ascended through the gears into creative overdrive with just one song.

Davies says it was his fascination for Eleanor Rigby in 1966 that compelled him to make contact with its writer Paul McCartney. It was fortuitous for the friendship that ensued led to him writing the only authorised Beatles biography - a work that started Davies on the road to prolific authorship.

Now, 40 or so books later he has returned to the band for his latest work – The Beatles Lyrics: The unseen story behind their music.

And of all their songs, Eleanor Rigby remains Davies’s favourite.

“I suppose one of the reasons I like the Eleanor Rigby lyrics best is because the song was my introduction to The Beatles,” he tells me. “That was the one I went to see Paul about; to ask him where the words had come from. I still think they’re terrific.”

Yet Davies is compelled to admit that despite the group’s prolific output in the 1960s and the adulation the Fab Four engendered, he never believed interest in them or their songs would endure.

“Like lots of others, I was a big fan of The Beatles,” he says. “But I thought their popularity would fade, just because of fashion.

“I didn’t believe they’d become classics, even though I loved them dearly. I thought in 20 or 30 years’ there’d be other more creative composers and singers of popular music. I also thought there’d be people who’d sell more records than the Beatles. Yet the further we get from them the bigger they become.

Indeed, Davies is astounded how much of a global industry The Beatles remain.

“When they finished as a band in 1970, their company Apple employed around 50 people,” he says. “Today, there are probably 5,000 people around the world whose main income is associated with The Beatles.

“I’m surprised that they remain so influential. I never thought they’d be studied at universities as an academic subject. At any university from Carlisle to Cambridge you can do a thesis on Beatles music and you’d be applauded for having a good idea; whereas in the 1960s and 1970s you’d be ridiculed for trying to carry out serious research on popular songs.”

He says one professor from York wrote a 30,000 word thesis just on Eleanor Rigby, likening it to an opera of ballet.

But - pre-Eleanor Rigby - what did The Beatles themselves think about many of their lyrics being dismissed as “simple and banal”?

“When I talked to John about it many years later he said, well the words of Strawberry Fields were no less important than Love Me Do,” says Davies. “He said they’re just words. Words are just words to sing along to.

“In the book I try to explain that’s how you wrote pop songs at the time. That was what the market wanted and that’s what - The Beatles had grown up singing and writing themselves. So, to try and get published and writing songs they were following the fashions of the time. It’s only with developing confidence that they realised they could write about things other than Love Me Do.”

For the lyrics book, Davies spent a long time tracking down original scraps of paper they were written on - either in John or Paul’s hand, but sometimes George’s. Often they were scribbled in the studio with amendments and lines crossed out, sometimes changes were made just before recording. Odd scraps, written in notebooks or on the backs of letters and left lying around, were given to Davies by Paul and John. These are now exhibited in the British Museum.

“Eventually I realised they were valuable and wanted them out of the house; but the main thing is I wanted them all kept together as a collection. I got them for nothing and Paul would never speak to me again if I sold them.

“Other people over the years who were given gifts from Paul and John, almost all of them as far as I know have sold them because they needed the money. I haven’t needed the money enough to sell them. I just wanted to keep them together. Back in the 1980s, the British Museum accepted them on permanent loan and displayed them next to Magna Carta and that’s amazing.”

I ask if that fact alone elevates The Beatles to some greater historic significance; and suggest that may one day be seen in the same creative light as, say, Shakespeare. Hunter is dismissive of the notion.

“History will obviously not see the Beatles in the same light as someone like Shakespeare; but in our British culture the Beatles have a place and they’re valued, respected and admired and they’re now classics in the sense it’s hard to measure a time or on the planet that people won’t have the breath to hum the tunes. I think they’re here to stay.

“It’s 95 per cent the music and just five per cent the Beatles themselves. Of course, there’s the cult of John Lennon and his tragic death. But it’s the music we love them for – and that’s what matters.”

The unseen story behind their music by Hunter Davies is published at £25 by Weidenfield & Nicolson.