The 33-year-old singer, here to promote his first solo album, is one of those American superstars who barely register on the radar of the average British pop fan. Think Dave Matthews Band, Hootie & the Blowfish and Third Eye Blind. And Thomas's band, Matchbox Twenty.
In America, their 1996 debut, Yourself Or Someone Like You, has outsold Sgt Pepper's Lonely Hearts Club Band, Nevermind and The Joshua Tree. Thomas was also the voice (and co-writer) of the guitarist Carlos Santana's comeback hit, "Smooth", and has written with Mick Jagger, Willie Nelson, Marc Anthony and Bernie Taupin. His publicists calculate he has contributed to album sales of 75 million.
It puts him in the enviable position of being rich without attracting too much attention - at least in London. "Last time I was here we sold out Wembley Arena to 11,000 people but I could still walk down the street naked and no one would know me," he says. "You don't get the fame but the money comes with you, which means I still get to stay in nice hotels."
The child of an army family, Thomas had a fractured childhood - but at 17, after being arrested for armed burglary, he fell in with some local musicians. "In songwriting I felt special for the first time. And all I wanted to do was get out of Florida."
Thomas played in various local bands before forming Matchbox Twenty. The band toured relentlessly, and were rewarded with a breakthrough hit, "Push". Then his publishers suggested writing with Santana. On the back of the all-star Santana album's success, Matchbox's debut passed 10 million sales three years after its release.
Yet music magazines and musicians frequently make Thomas the butt of their insults. From meeting the loquacious and likeable singer, it's hard to understand why.
"It's because our music is mainstream, and when it became successful that was the nail in the coffin," he says. "We started off as an alternative band. Before we sold any records, the reviews weren't that bad at all. We were this earnest band writing good-quality songs. Then we slowly sell more and more albums and suddenly we're like the Backstreet Boys.
"We were never gonna be a band that was cool or hip," he says. "We knew we weren't Led Zeppelin or Iggy Pop or The White Stripes. I grew up on radio, and whatever I write, it's always gonna come out with a radio sensibility. Maybe we did make music for the masses. At the end of the day we are the masses. So it was that moment where we stopped worrying about being cool.
"I literally don't remember the first couple of years when we started taking off in the States," he adds. "I was like every kid who ever signed a record deal and sold some records." He was drinking heavily, had a big cocaine habit and his weight soared. "The shows were starting to suffer. I would do a lot of coke but just so I could stay in the game."
The band made a conscious decision. "We sat down and thought: 'there must be more than this'. How about if we cleaned ourselves up and started to really focus? We became these task masters all of a sudden because we could see it going away."
The other positive factor was Marisol, Thomas's wife - half-Spanish, half-Puerto Rican and the inspiration for "Smooth" and much of his solo debut, Something to Be. "We met seven years ago in Montreal," he says. "She was dragged to our show by a friend, who got them into our party afterwards. It was a storybook case of love at first sight."
For the past two years, Marisol has suffered from a rare cell-tissue disorder. It has been a difficult time. "'Now Comes the Night' is a song about death but also a song about love," Thomas says. "Great love all of a sudden brings to mind loss and mortality because you suddenly start thinking about the time you have left with this person.
"And 'Ever the Same' was about her being really sick and being so frustrated by it that she would keep me at bay because she felt she'd be bringing me down. It all stemmed from the line: 'Just let me hold you while I'm falling apart.'"
'Something to Be' is out now
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