Although generally regarded now as a darling of the safe country-MOR set, Glen Campbell’s pedigree ranges way beyond the genre, taking in stints with acts as musically diverse as Johnny Cash, Merle Haggard, Ray Charles, the Mamas and Papas, Frank Sinatra, the Beach Boys and Phil Spector, plus symphony orchestras and jazz combos.

So from that impressive career, is there one musical memory that he looks back on with particular fondness?

“Actually I had a really good time working with that Irish folk group, what was their name? They were real big in the USA.”

He thinks for while, as I prompt him with a few suggestions of my own. Clancy Brothers? The Chieftains? Clannad?

Then he remembers: “They had a hit with that song ‘The Unicorn’. I did some production work with them”.

I tell him it was by the Irish Rovers and he then treats me to a live snatch of the chorus all the way from his new home in Malibu. You had to be there.

Campbell grew up in the early '40s, in an Arkansas family with Tipperary connections. Music, he says, was unavoidable.

“There were 12 young Campbell children and we nearly all played guitars and sang,” he remembers. “In fact, I got my own first guitar when I was only four or five. There was so much music around that I don’t even remember when I played my first gig in public, although I did tour with my uncle who was a musician called Dick Bill.”

Another important influence was the music of Jimmy Webb.

“‘By The Time I Get To Phoenix’ by Johnny Rivers is one of my favourite records. I bought it on a 45. It was written by Jimmy Webb. I really fell in love with Jimmy’s songs and had hits with more of his numbers like ‘Witchita Lineman’ and ‘Galveston’. His melodies were always so good and he’s right up there with such other great pop composers as Bacharach and Hal David.”

Another early influence was legendary country guitar-picker Chet Atkins.

“I loved all that ‘country gentlemen’ thing, and he was a terrific guitar player. But I didn’t really think of just playing country music as such. I used to be drawn to something I liked and I didn’t worry too much what category it came from.

“If you look at the artists I’ve played with over the years, it goes way beyond just country music. Actually, I like to think of myself as a jack of all trades. I like that kind of musical variety.”

Mind you, Campbell came from a less than well-off background.

“We were really poor and we had to make money any way we could, maybe picking potatoes or tomatoes or driving trucks or fishing. Whatever it took to put food on the table. I even picked cotton, although I got out of that as quick as I could."

Are there any new artists he really rates?

"Keith Urban is a fine performer and a fine guitar player too,” says Campbell, no mean guitar player himself. Not that his chops were of any use when playing for the Queen.

“I remember one strange incident only a few years ago," he says. "I was in London doing a concert for the Queen Mother and everything was going fine and then the microphone I was using started slowly disappearing down through the stage. So I had to keep adjusting my position so that I could keep singing into it!”

Luckily he got to the end of the song before the mike disappeared completely.

“Thankfully, nobody seemed to notice. I guess they just thought it was part of the act.”