IT’S hard to believe that someone playing guitar in front of up to 250,000 adoring fans this weekend could be harbouring a small degree of frustration.

But Nils Lofgren – surely the most over-qualified second guitarist in the world after 25 years alongside Bruce Springsteen – knows that the hectic schedule headlining Glastonbury and Hard Rock Calling means he’ll miss out on meeting up with his oldest rock mentor.

Nils was just 17 when Neil Young brought him in to play with his band on the acclaimed After The Goldrush album.

More than 40 years on, the two will be on the same stage, at the same festivals... but 24 hours apart.

Young plays Glastonbury on Friday and Hyde Park on Saturday, while Bruce and the E Street Band take the prime Pyramid Stage slot on Saturday night and rock the park on Sunday.

“Sadly, just like last year, there are no dates of Neil’s that I can make without travelling on our own show dates. It’s really a shame, but it’s just too dangerous to travel on a show day, especially in Europe.”

Those 40 years on the road have established Nils as one of the most respected guitarists in the world.

After a six-year stint in the early ’70s that saw him form his own band Grin as well as tour and record with Young, he launched a solo career in 1975 that spawned more than 30 albums, most recently a covers album of classic Neil Young songs The Loner – Nils Sings Neil.

But it was in 1984 that the call came that would shape the rest of his career.

Bruce Springsteen drafted Nils and backing singer Patti Scialfa into his E Street Band ahead of the Born In The USA tour that cemented The Boss’s reputation as one of the top live performers in the world.

Patti was eventually to become Mrs Springsteen, but for Nils the experience of being part of this rock behemoth never ceases to thrill or surprise, especially on recent tours when fans have been dictating some of the show’s two-and-a-half hours-plus content.

“It’s such a great adventure,” he said. “Bruce has got into this total ‘improv’ thing, with signs and requests from the audience. It’s a great way of challenging himself and the band.”

But as well as plucking rarely played songs from Bruce’s own back catalogue, even Nils has been surprised at some the fans’ more obscure requests.

“Increasingly there are shows where we’re playing songs that we’ve never played in our lives, so learning a song that you don’t know how to play on the spot and then performing it is a new one on me!

“But there’s no better band equipped to do that, so we have a quick huddle on stage and give it a shot. It’s a fascinating and exciting challenge.”

Nils is also forging a reputation as the E Street band’s Mr Versatile. As well as playing several kinds of guitar with Bruce, he’s also an accomplished pianist and accordionist, an instrument he mastered as a youngster playing folk songs for his Italian mum and Swedish dad.

Indeed, the Scandinavian leg of the tour offered the unlikely sight of Nils leading the greatest live band on the planet out on stage to the strains of a popular Swedish folk song... and then partying after the gig with 30-plus cousins.

Ahead of this weekend’s festival weekend and second European leg of the tour, Nils has been relaxing back at home in Scottsdale, Arizona, with his wife Amy, stepson Dylan and their menagerie of dogs and cats.

But he’s hoping to have time to record more of his online guitar lessons for both beginners and intermediate players via his website nilslofgren.com, including some of the complex solos that have become an integral part of the E Street Band shows.

“It’s about teaching people to play guitar who think they don’t have any talent, imparting some knowledge and making sure people have fun learning.”

But Nils fans missing his regular solo visits to the UK will be heartened to know that he’ll be planning a 2010 tour as soon as the Springsteen commitments end around September.