When life is tough, people turn to gospel. Just ask the head of The Kingdom Choir, Karen Gibson. If that choir name sounds familiar, it should, because it belongs to the group who delivered a dazzling three-minute performance on May 19 as the Duke and Duchess of Sussex were married at Windsor Castle.

It was an austere day, with thousands gathering to fight for a glimpse of Meghan's dress or Harry's shock of red hair.

In the middle of all this was The Kingdom Choir – a talented but unknown group of gospel singers invited to perform.

Gibson guided them through a soul-stirring rendition of Stand By Me by Ben E King and from that moment the group's fortunes were changed.

"We never saw this coming. We never saw any of it. It's been amazing. It's been a real whirlwind," Gibson, 55, acknowledges down the phone from her London home.

"It's an undreamed dream. It's a dream that you don't dare dream. Every day is different now, every venue is different, every performance is different."

Gibson's crop of silver hair made her the recognisable symbol of the group, which counts about 30 but flexes in number to suit the occasion.

The Kingdom Choir, she explains, existed for many years before the public took notice in May, but the fact their attention is drawn now is no coincidence.

Last year, grime artist Stormzy bucked expectations to release Gang Signs & Prayer, an album of gospel and soul.

And each year the Music Of Black Origin (Mobo) awards draw more attention to the genre.

Gibson sees her music's success as a sign of the times, and when the chips are down, people turn to gospel.

She explains: "We are in a season when people need hope. They want to be inspired. People want goodness in their lives because there seems to be so much bad news all the time.

"People want love. They want to feel love and they want to be loved, and people also want to be free.

"I have also seen how singing frees people and how it creates great connection. People want family, and singing in a choir provides great family."

She started her first choir in 1994 with sister Kimmie and school friends Elaine and Collette in south London's Tooting. Later, she went on to sing backing vocals for acts like Grace Kennedy and The Beautiful South and, until the royal wedding shot her to fame, taught in schools around London.

In the days following the wedding, members of the choir became household names. The YouTube video of their performance has currently been watched more than five million times.

The group are also releasing an album, titled Stand By Me after the song that changed their lives. It features modern covers of Bob Dylan, Stormzy and Beyonce while delving into R&B, soul and, of course, gospel classics.

Recorded over two weekends, Gibson says the studio time challenged the choir.

"We were very tired by the end of it but we loved it. There's nothing wrong with being intense and tenacious and intentional and purposeful. It's good for the soul," she says.

"It was a great time of collection and fun and great music, wonderful arrangements from our fabulous arrangers, and a lot of love, a lot of laughter, a lot of food and biscuits."

Gibson's voice holds a preacher's power. This is clear even over the phone. The way she forms her words is strong and compelling but also soothing. It's not hard to see how she inspires the rest of the talented singers - many of whom see her as a kind of spiritual leader.

Ayanna Mitchell from Edgware, north London, was among those who sang at the royal wedding and speaks of Gibson with an almost religious fervour.

The 31-year-old met Gibson at a New Year's Eve party in 2014. The pair discussed gospel and by the end of January she was part of the choir.

Mitchell describes Gibson as a "leader, friend, confidante, spiritual mother".

"(Gibson) wears so many different caps, and she wears them so well," she says.

"She loves deep and hard, and carries an incredible amount of respect that I believe is unmatched. Her impact is undeniable. I just suppose it is what she carries in her character."

Vernon Samuels, another choir member and Gibson's brother, repeats the same mantra, but highlights her no-nonsense leadership style.

"There are no easy rides in The Kingdom Choir. You are expected to pull your weight. She has a high expectation of all," he says.

Samuels, a former triple jump Olympian who at 54 lives in Bristol with his wife, tells me gospel's time is now.

"Many or all of the choir have been involved in the gospel scene for as long as 30 years. There's been an undercurrent for that long and it's finally starting to break through."

Like the rest of The Kingdom Choir, Samuels is convinced gospel has finally broken into the public consciousness, and he puts that down, at least in part, to the royal wedding.

"I don't think you can underestimate the wedding as a platform for showing the talent of The Kingdom Choir - and the true power of gospel."

The Kingdom Choir's debut album Stand By Me is out now.