ELTON John means so much to his fans. Take the woman who, having paid for the privilege, went on a backstage tour at her 19th Elton concert and subsequently described sitting at his piano as an “almost spiritual” experience.

Davey Johnstone, Elton’s Edinburgh-born, long-serving guitarist and musical director, knows exactly what the fan is talking about. He has played in excess of 2000 shows with Elton all over the world, but never takes the connection with the fans for granted.

“It’s a wonderful thing”, he says by phone from California, where he lives, “because you suddenly feel like you have been a part of people’s lives, more than you’re just doing your own gig and simply going through it.

“Like, for example, when I’m up at the market here, which is something that I can do, because I’ve never really embraced the rock-star kind of lifestyle, somebody will come up and say, ‘You don’t know me, but you guys’ music was there for me during my difficult years’, or something like that.

“And you suddenly go, “S***, I’ve actually played to a lot more people than I thought, be it [a] live [concert] or whatever, and, more importantly, have been a positive source of enjoyment. It’s a very privileged thing, actually: I feel very humbled when people come up and say stuff like that. It’s like an affirmation that you’ve done something worthwhile.”

Having recovered from his recent bacterial infection, Elton is on the road again, accompanied by a band that, naturally, includes Johnstone. The solitary Scottish gig is on June 24, when they play Airdrie FC’s Excelsior Stadium.

In previous interviews Johnstone has recalled the day at primary school when musical instruments were being given out and he volunteered to take on the violin. He was just seven years old. By the time he was 10 he was playing it “sideways like a guitar”. One of his sisters noticed, and bought him a guitar for Christmas. At the age of 12 he was organising bands in Edinburgh's Forrester High School: he had already decided he wanted to be a musician when he grew up.

In time, he moved to London and played in a number of bands, including Magna Carta, one of whose albums was produced by Gus Dudgeon, Elton’s producer. In 1971 Dudgeon asked him to contribute to a solo album by Bernie Taupin, Elton’s lifelong songwriting partner. Later that year, Johnstone was asked to play acoustic guitar and mandolin parts on Elton’s Madman Across the Water album. Elton quickly invited the Scot to join his band, alongside drummer Nigel Olsson and bass player Dee Murray. Johnstone without question had the musical chops but as author Tom Doyle wrote in his book, Captain Fantastic, he also looked the “hirsute rocker part with his long wavy blond hair”.

His debut was at an Elton concert at London’s Royal Festival Hall in February 1972, the second half of which saw Elton backed by the 80-piece Royal Philharmonic Orchestra. It was the the start of a whirlwind period for Johnstone with the flamboyant Elton: chart-topping singles and albums, and endless tours in which the band criss-crossed the globe.

His work on the guitar, mandolin, banjo and harmonica have graced so many Elton classics. To take one well-known example, the eerie slide-guitar on Rocket Man, Elton’s early smash hit, is his. He has co-written various songs with Elton, including I Guess That’s Why They Call It the Blues, and in his time he has also worked with countless other stars, including Alice Cooper, Meat Loaf and Rod Stewart. He has, in short, had a remarkable career.

Johnstone talks entertainingly about some of the Elton concerts that have remained with him, such as the hugely successful gigs at the Dodger Stadium in Los Angeles, in October 1975.

“We were in our trailers backstage, and there were all kinds of people coming up – stars from the current time of TV and movies, and old-timers. We were used to that: we’d always get Groucho Marx, or Mae West, some real old icons like that.

“One day at the Dodger Stadium, the wife of one of the band says [he puts on a London accent], “‘Ere, that’s Gary Cooper outside the trailer!’ I said, ‘Well, Gary Cooper’s been dead for years’, but I look out of the trailer and it’s Cary Grant, and I was like, ‘Holy s***‘, because he’s one of my favourites… These were amazing gigs.”

Elton’s most recent album was the upbeat Wonderful Crazy Night, which came out last year. It turns out that he phoned Johnstone and told him, “I want you to go out and buy some 12-string guitars. We’re going to make up a very up record”.

Johnstone laughs as he confirms the story, and he talks about how the album was made. “It was a really good experience and we look forward to the next one, whatever that may be.

“When you work with somebody as talented as Elton, you’ve got to be prepared for, ‘Well, this is what I want do to’. This is what will come out of his mouth, and you’re looking at him, like ‘What?’

“Most of the time I’m on the same page as him, because we’ve got a really close musical bond. We’ve built up a good friendship over all these years but we’ve also got a very close mutual understanding, which is why he lets me run all the rehearsals on my own, without him even being there, most of the time”.

Elton may have turned 70 years old but his appetite for live performance remains undiminished, which means that Johnstone’s diary between now and next March is heavily laden with dates in Europe and Australia. The band’s first-ever concert in Beirut will take place in December. Elton has also lined up a string of Million Dollar Piano shows in Las Vegas, this autumn and next spring.

Johnstone himself turned 66 last month. It’s just as well that his appetite for touring, for new experiences, is as fresh as it ever was.

“We did a tour in South America this spring, with James Taylor opening for us, which was rather cool”, he says. “It was a strange feeling in a way, although one of the things about Elton and me, and the way we work, is that our whole dynamic comes from the fact that we don’t care if we’re opening for anybody. We don’t care who’s on before us. We’re going to go out there and slay 'em.

“And, as a result, we’ve done a bunch of festivals over the last five or six years, which has really reaffirmed Elton’s belief in the fact there’s a huge audience out there for him.

“Our smallest gigs are usually about an average of 10,000, and then we’ll play to an audience of about 40,000 or 50,000, as we did in South America. And on a couple of the upcoming stadium dates, there will probably be 30,000 or 40,000 people there. For a band that plays as often as we do, that’s a huge audience.

Some of the concerts are in out-of-the-way places that top groups rarely visit such as Missoula, in Montana; Porto Alegre in Brazil, and London, Ontario.

“It’s a bit of a challenge to get there, and it’s a bigger challenge for the [road] crew to take our show to places like that”. But it’s worth it, he says, “because the people love the music, and they’ll come back to the bigger towns to see us, and people from the larger towns will go to small towns to see us there.

“That’s the thing”, Johnstone adds. “It’s the willingness to go and play in some of those places which has always kept us going. But the downside is that it has cost us a lot of health problems. Apart from the fact that the gigs are very strenuous, we’ve done a lot of travelling to get to bizarre places.”

At the time of the interview, Johnstone was enjoying some time with his family. His home looks out onto the back of the Santa Monica mountains. “I’m about five miles from the beach, and right by Malibu Canyon”, he says. “It’s brilliant over here, it really is. The wildlife is amazing: we’ve got coyotes, rattlesnakes and tarantulas”.

He laughs. “The other day we had a banded centipede, which was quite a terrifying little thing, which I’d never seen before. But, you know, these are the breaks – if you want to live somewhere bizarre, then you got to put up with the wildlife. And I love it. I love it here”.

Tickets for Elton John’s Wonderful Crazy Nights tour at Airdrie’s Excelsior Stadium are available at www.ticketmaster.co.uk/eltonjohn