How we met: Jamie Cullum & Laura Mvula

'He described me as serene and regal. But I wasn't moving because I was so scared!'

Jamie says of Laura: 'She's the most tranquil presence on stage' (Donald Maclellan)

Jamie Cullum, 33

After releasing his debut album in 1999, Cullum's TV appearance on 'Parkinson' in 2003 exposed the jazz-pop singer to a wider audience – and his third album, 'Twentysomething', released later that year, became the bestselling UK jazz album of all time. He lives with his wife, model-turned-food-writer Sophie Dahl, in Buckinghamshire.

I heard Laura's music long before I met her. I have a show on Radio 2 and the number of music demos I'm sent is terrifying. But I saw this EP from Laura, and as my manager had mentioned her name, I played it. The second I put it on, I was moved. It was a jewel of a song: the arrangement was appealing and it was melodic, adventurous song-writing.

After my show I tweeted that I'd played it and that Laura would be massive star. She saw it, tweeted me back and three days later, there was a headline for an interview she did that said: "I cried when Jamie Cullum tweeted me." I found it moving as I had no idea she had been a fan of mine since she was a student.

I asked her to come sing with me at a live session on one of my new songs I was doing at Abbey Road studios, for a deluxe edition of my new album Momentum. I remember seeing her walk down the stairs and thinking that she was every inch the serene beautiful person I'd seen on the album cover. She was sweet and warm and within five minutes we were singing together. Her voice made the band play differently, she slowed the tempo down – it was new for us, but it felt really natural.

She's more confident than I ever was at that stage in my career. The first time I performed live, I was a sweaty mess, closing my eyes and rocking around. But when I watch her perform live, she's the most tranquil presence on stage; she looks to a point in the sky, like she's looking up into the heavens.

We got to hang out at the Cheltenham Jazz Festival recently. There are jazz colours to what she does, though I wouldn't call it jazz. She has a musical adventurousness, which is also the link to our music. There's a quality to her voice that doesn't easily fit into the pop mould. I don't know why some people call her the next Adele, though – the only thing they have in common is that they're female.

When you're in the eye of the storm, stuff happens. Just before she was due to leave for her American tour [which begins today] she lost her passport. She called me up to have a rant. I was like, "Don't worry, I've lost my passport 10 times," and I put her in touch with people who could sort it.

When you're riding a wave of critical acclaim, you're promoting, doing stuff all the time and barely stopping to concentrate on the music part. So the only thing I advise Laura is to keep her house in order by keeping her focus on the music.

Laura Mvula, 25

Following her nomination for the BBC's Sound of 2013 poll, the classically trained Mvula garnered critical acclaim for her debut album 'Sing to the Moon', which charted in the top 10. She lives in London with her husband.

My earliest memory of Jamie's music was hearing his cover of Radiohead's "High and Dry" while I was a sixth-form student. I fell in love with his music and worked my way through his back-catalogue, buying all his albums. With his voice, I thought he was a much older guy initially. I became intrigued by his energy, watching his performances where he'd play the piano, before jumping up and dancing on it.

We first connected last year, over Twitter. My album wasn't out yet and I was at home in my pyjamas, babysitting my goddaughter when I saw this tweet from Jamie saying he thought my EP was incredible and that he was looking forward to the album. For me it was like wow, and it didn't sink in for a long time.

His management got in touch soon after and asked if I'd sing on a song he recorded for Momentum. For the Abbey Road live session I had to make an entrance from the top of the stairs to where the band was playing. I'm quite shy, so I was like, please let me enter without being seen. Halfway down, though, he stopped everything in the room. I was so nervous but he greeted me with open arms.

Watching that performance now, it's interesting to see how much he moves around being silly, while he describes me as serene and regal. But I wasn't moving as I was so scared! Even now I still pinch myself.

I have struggled a bit with the pace of my career, so sometimes I'll ask him, how did you cope with all this? And he'll say, "You know, the music always has to come first."

We did another performance together at [London live-music venue] Heaven to promote his new album, which is where I met his wife, Sophie [Dahl]. I fell in love with her instantly. She's a beautiful woman and was so wonderful and calming; she could recognise the whirlwind I was in and she seemed genuinely excited for me. They are a stunning couple. One of the songs on Jamie's album is a cover of "Pure Imagination" [from the musical version of Sophie's grandfather, Roald's, Charlie and the Chocolate Factory], and it's one of my favourite songs of all times.

I don't think Jamie knows how hardcore a fan I am. I've a couple of friends who share my love of him. A few years ago one of them asked me to perform at her wedding, using Jamie's arrangement of "If I Ruled the World" and I massacred it. It's on video somewhere and, having met Jamie, I hope it never comes out!

Mvula's album, 'Sing To The Moon', is out now. Her UK and Ireland tour starts on 30 September (lauramvula.com). Jamie Cullum's new album, 'Momentum', is out tomorrow