"AM I unstoppable? You could call it that!" Candi Staton declares with a grin. The soul singer is keeping a low profile in a baseball cap and sunglasses, as we sit in a quiet corner of a hotel dining room. The previous evening, the 78-year-old had played an intimate show to launch the 30th album of her career, Unstoppable.

Staton cites life in Donald Trump's America and the injustices African Americans face as motivation to continue some five decades after she first reached the US charts.

"This album speaks to the now," says the Alabama-born singer. She is almost whispering, but her voice strikes a determined tone. "When Dr Martin Luther King was trying to change things in the Sixties, Mavis Staples came out with songs like Respect Yourself. It spoke to what was actually happening politically and racially. This album does the same thing.

"I'm encouraging people because there is so much bullying from the top. It's amazing how people are cowering under it. We don't know what to do. The Senate is deaf and dumb. They don't say or do anything. Bills are passing, we don't know what they're doing in the dark. There is so much uncertainty now.

Staton was born back in the 1940s. "We had prejudice and all that kind of stuff. It's not prejudice in the form of segregation now. It's in blue suits with police sitting up there on it. So it's changed, but for the worse. We're having a lot of problems with racism. It's just blatant."

She began singing in a gospel group with her sisters when she was a teenager, touring with the likes of Mahalia Jackson and a young Sam Cooke.

"I was 14 when I met Sam. I never knew Sam was going to be who he was," she says. "We got to be friends and we'd just sit and talk. He wasn't a big star, he was just the lead singer of a gospel group. He was one of us. We'd arrive early at the school auditorium where we'd be performing. One of us would have a ball. We'd get a plank, not a baseball bat, just some old plank, and we'd play ball!"

Religion has been the foundation of Staton's life. Her faith has guided her through many difficult periods, including a battle with alcoholism that lasted over ten years. At the start of her career, she found herself caught between touring and raising a family - and developed a taste for champagne at record company parties and became dependent on alcohol to perform.

She vividly recollects the day she decided never to touch another drop. "I got so drunk one night. I had lost it. It was in August and it was hot. I was in Alabama. We were swimming. I was sat there on a big ol' rock. I had a hangover. I started crying. I said, 'This is not like me, I don't know what I'm doing with my life'. My kids were worried.

"It was though I could hear my mother's voice. She said, 'You need to fast. Fasting breaks things'. So I sat there in the waves and said, 'Lord, I wanna be as solid as this rock. Can you make me as solid as this rock?' All of a sudden, I said I wasn't drinking anymore, or eating until this is broken. That was in the Seventies. I've not had another drink since."

Staton admits her faith was also tested during a string of abusive relationships and difficult divorces. The lyrics of her disco anthem, Young Hearts Run Free, were written while Staton was seeing what she calls one of her "bad guys". She remembers him holding her over a banister at a theatre she was playing at in Las Vegas with Ray Charles, and threatening to drop her.

Staton is happily married to her sixth husband now, a former US secret service agent who worked as a bodyguard for four presidents. They were introduced at a church where Staton was doing charity work supporting victims of domestic violence.

"I married a wonderful man. It was strange because I've been used to the wrong kind. I wasn't used to anyone that straightforward or so well respected," she says. "We have a good relationship. We see each other once or twice a month. He works in Memphis, while I'm based in Madison, Georgia. I'm not giving up my house, and he's not giving up his. I go home for two or three weeks, he comes to Madison for a while, then goes back. He understands all that."

Staton's career was rejuvenated in the Nineties, when a song she recorded for a diet commercial was remixed and released by London DJ, The Source. You Got The Love was a hit across Europe.

"The story of that song could be a documentary," she says. "It was on the shelf and I forgot it was even out there. And when people told me it was in the Top 10 here in Europe, I was floored. I was like 'You got me mixed up with somebody else'. Then I got a call from a DJ asking me to talk about You've Got The Love. And then it clicked. 'Oh that song I did in Chicago in '86 for that diet thing!' When I heard it, I didn't recognise it. I'm a straightforward R&B and soul singer, so it was kind of like, 'okay, but I'm not going to do this stuff'. But I did!"

The song has been covered many times. As our conversation draws to a close, I ask Staton whose reworking she likes the best.

"Florence + the Machine did a good job. We did it at Glastonbury and she recorded it on her phone. I was going to do it like that on stage, but she beat me to it!"

* Candi Staton's new album Unstoppable is out now.