"He was a storyteller. Sure he had a different sort of voice, but it was a lot better than he gets credit for. There was a talking aspect to the way he sang, but he had an aggression about the way he sang, too. It was physical and you've got to put power into the way you perform the songs."

He says it's not too hard on his voice, more on his body. "You've got to be sensible. Once you get to the stage you just go out and do it, it's easier."

He has no illusions about his success and doesn't think he would give up paying tribute to Cash to do his own thing.

"Maybe one of these days. This business is tough and I have it good doing the Johnny Cash tributes. Who's to say anyone would want my own music."

His Back To San Quentin - 50 Years On tour doesn't let up until the end of September and he looks forward to performing at the Glasshouse again.

"Standing on that stage - it's really nice; all the woodwork around the room. It's a fantastic theatre, there are not a lot where you can say 'this place is amazing'.

"We have a reputation for what we do and the crowd knows that. We have a new guitar player this year, Roy Payne, he's played with Don Walker. He's doing a fantastic job. Great singer Rebecca Lee Nye is with us for some June Carter numbers."

You can't talk about the San Quentin concert without A Boy Named Sue coming up. "That was obviously the biggest song of Johnny Cash's career. We always play with that one a bit; tell the story about how it came about," Thompson says.

"He'd only heard the song a couple of days before. The band didn't know the song, and he had the lyrics in front of him. Cash had a reputation of just starting singing when he felt like it, and if you watch the videos you can see the band watched him like a hawk to know when to kick in."

Thompson says if the album was just a studio recording it wouldn't have had the life it did. "He had the audience on his side by then. It was a bit raw, but everything came together. There are 10 verses of the song. I have my moments when I've had no idea what was coming next. The good thing is the audience sings along, so if you forget words they just fill in the blanks."

There is obvious admiration on Thompson's behalf for what Cash did by performing at San Quentin. "He knew these were bad guys, but he also knew they were men that needed something, and he could give it to them. He helped the mood of those places and he got a lot out of it. He calmed things down. He had the power to change people's live."

Cash helped a few ex-prisoners on their release. "He had one get out of jail and go on the road with him, but it didn't go that well. Merle Haggard was an inmate of San Quentin sitting in the front row when Cash did the first show there."

This time 'round, Thompson and his band do "a whole lot of the songs from the album", plus fan favourites - Ring of Fire, June Carter duets and a few from album Out Amongst The Stars, released just a few years ago, but recorded in '84-'85 during a down time in Cash's career. " It slipped through the cracks at the time when he had a dispute with the record company. It's nice to think we can still hear new music from him," Thompson says..

He will come out to have a chat with people after the show. "Hearing people's memories of what it meant to them, growing up with their parents listening to Cash, that's a privilege.