SO, let’s start with a question. What had you achieved by the age of 19? If I remember back to the last century all I can be sure of is three A levels, the prospect of a Scottish university place (Stirling of course; redbricks rule!), a decent collection of Marvel comics and seven-inch singles, a personality shaped by shyness and spots and a Boy’s Brigade traffic safety award (our team were runners-up). Oh, and a girlfriend from about halfway through.

I know, I know. Impressive, right? And then you think about someone like Sheku Kanneh-Mason who is 19 and who just possibly outdoes my dazzling success.

The teenage cellist does have a number one album, Inspiration, to his name, as well as millions of views on You Tube for his shimmering take on Bob Marley’s No Woman No Cry. He also picked up a couple of Classical Brit awards in June. And then there’s the small matter of being named BBC Young Musician of the Year. And that was back in 2016. When he was even younger.

That said, I doubt he has a nearly complete run of Marvel’s Master of Kung Fu (though in the interest of full disclosure I admit I didn’t ask). Nor I suspect he doesn’t have a copy of Kid Creole and the Coconuts’ single I’m A Wonderful Thing Baby with its original wraparound poster in mint condition.

But I grudgingly do accept that his teenage years may have been more productive than my own. Just.

And, actually, looking back over that long list of achievements (his, not mine) I realise I’ve missed something out. What was it? Oh yes, the small matter of playing a Royal Wedding. Three billion watched him playing pieces by Maria Theresia von Paradis, Franz Schubert and Gabriel Faure for Harry and Meghan and assorted celebs and posh people at the bash in Windsor Castle in May.

Really, you would think by now his ego should be the size of a small planet and he should be running around half-naked, covered in glitter and calling himself Jesus.

But I guess they don’t do that kind of thing in the world of classical music. Because the young man I talk to turns out to be well spoken, polite and anything but egotistical. Possibly he does the big-headed Jesus thing every alternate Wednesday in months with an N in their name. But that’s not today.

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How, I must ask, have the last couple of months been for him, then? “It’s been very busy,” he admits. “But I’m enjoying everything that’s been happening. I’ve had the opportunity to perform in lovely places and that’s what I’ve always wanted to do. I’m just enjoying it.”

Even so, I say, has there ever been a point where you’ve looked around, Sheku, and wondered, well, how did I get here?

“Sometimes,” he says laughing. “My life is very different now to how it was two years ago. It happened very quickly, but it’s what I’ve always wanted to do.”

Sickeningly grounded, I hear some of you whisper. Well, yes, but he’s not perfect, you will be keen to know. When we speak his phone keeps cutting out and he could clearly do with an upgrade. Plus, he says he loves football, yet he turns out to be an Arsenal fan (a contradiction in terms, I’d say but then I my own allegiances lie with other team from north London).

Oh, and as well-spoken and polite as he is, he also doesn’t say much. As in almost nothing. Ask him questions and he keeps his answers brief and to the point. I quiz him about the Royal Wedding. Half a dozen questions at least. Counting the words he uses to answer them all I get no higher than the number 65.

But then again if I’m honest when I was 19 there were whole days where I wouldn’t say 25 words never mind 65. It’s a boy thing. (Then again, at no point does he descend into mumbling incoherence and that’s me pretty much every single day.)

Anyway, when we speak, he’s on his way to rehearsals at the Royal Academy. He goes in every day to practice. And then he’ll also play on his own every day. Four or five hours usually, he says.

“There’s no short cut. Practicing every day you have to really love what you’re doing. It’s important to be focused.”

And he clearly loves what he’s doing. He’s at his most forthcoming when he talks about music, about the music he plays, about the music he grew up listening to and about the cello itself.

“I just love exploring the range of sounds you can get from the cello,” he tells me, “from the sonorous mellow lower end to the really singing upper end. I really enjoy exploring that range.”

If anything, he says, it’s an instrument that gets more challenging the more you play rather than less. “There’s a realisation about how much more you can discover and the content becomes more detailed,” he explains. “So, I find that I’m constantly learning.”

Do you feel that you will master it one day? “I hope not. It’s an amazing thing to keep developing and have more and more ideas. I think that’s one of the greatest things about music. There’s no limit to it.”

It’s a big instrument, though, isn’t it? Watching him play made me wonder about the likelihood of injuries. Is there such a thing as “cello finger,” I wonder?

“Oh yeah, it’s important to stay relaxed. Any tension in the hands can cause injuries. It’s important to stretch.”

But he’s not been substituted from a Shostakovich gig so far? “No, I’ve had plenty of injuries from playing football but nothing from playing the cello.”

This summer sees Kaneh-Mason making his debut at the Edinburgh International Festival where he will perform with the City of Birmingham Symphony Orchestra (he worked with CBSO on his album) in a programme that takes in Stravinsky’s Funeral Song, Elgar’s Cello Concerto and Ravel’s Daphne et Chloe.

When you’re learning a new piece, I ask, is it just about the notes on the page or do you read around the subject? “I think it’s always interesting to read around the piece and read about the life of the composer,” he says. “I think you can also get a lot of understanding from the harmony and what the composer has written as well. It’s a combination of the two, I think.”

This is why Kanneh-Mason has got to where he is. He’s serious about what he does. And he’s serious about the music. In love with it. He’s been listening to Elgar’s Cello Concerto since he was four or five.

Conviction and love are nothing without talent of course. And he has that. It was nurtured by his parents who have in fact nurtured a whole family of musical talents.

Kanneh-Mason grew up one of seven kids in Nottingham. His mother’s roots are from Sierra Leone and Wales, his dad’s from Antigua. His mum Kadie Kanneh was a university lecturer and his dad Stuart Mason works for the Belmond luxury hotel chain. They are solid middle-class stock and yet holidays were sacrificed, house upgrades put off to allow all their children to take music lessons.

Kanneh-Mason remembers music always being part of his story. “I used to listen to a lot of music in the car with my parents and that’s what kind of got me into classical music. Lots of recordings of Jacqueline duPre playing the cello, Izthak Perlman playing the violin.”

If you and your brothers and sisters are all playing at home, I ask, did it ever get competitive? “No. I found it lovely to have two older siblings to look up to and take advice from, and, also, to have younger siblings to help with their practice. It’s a nice dynamic, I think.”

The Kanneh-Mason Kidz (as they possibly don’t call themselves) came to the fore in 2016 when they performed in front of Simon Cowell and Co in Britain’s Got Talent. Rather different than playing the Royal Albert Hall, Kanneh-Mason admits, but good fun. “The experience of performing in front of cameras was a great thing to take from it, so, yeah, it was enjoyable.”

You all weren’t upset about ultimately being beaten by a dog? “No,” he laughs and shuts up. He won’t be drawn on the taste or otherwise of the British public or at least that section of it who watch ITV during prime time.

And, anyway, he probably knew he would get other opportunities. The biggest of them came this year when the future Duchess of Sussex gave him a call on his mobile (presumably it was working fine that day) to invite him to perform when she got hitched to a Windsor.

Hence his appearance at St George’s Chapel blinged out in Paul Smith and playing his heart out.

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Kanneh-Mason is one of those performers that it’s a delight to watch. His face is so mobile. The connection between his fingers and his expression is electrifying.

What are you thinking of, I ask him, while you are playing. The music? The surroundings? What you’re going to have for dinner?

“Umm, lots of different things. I think a lot about the people I’m playing, each phrase I’m playing … It’s hard to put into words. I’m generally very focused on what I’m doing.”

Well, I’m guessing you wouldn’t want to think about the three billion people watching you on the day. Or look up and see Elton John or George Clooney or Victoria Beckham or James Corden, or, you know, the Queen. Might be distracting.

“I can see the audience, but it doesn’t distract me. I like to perform to people. It was very exciting to see all those faces. I just found it exciting.”

The thing I noticed most, I tell him, apart from the delicacy and precision of his performance were his socks. “They were some very cool socks,” he agrees.

I guess this is his world now. Being styled and groomed. “It’s quite nice actually. I enjoy it.”

Ah, are you a natural peacock? “Oh, I don’t know.” But you like dressing up?

“Yeah, definitely.”

The republicans reading this may now be mumbling and grumbling about the very idea of a royal wedding and telling anyone who will listen that the wedding was just a multicultural reboot for Buck House: “And now presenting Windsors 3.0.”

And I don’t necessarily disagree, though a wedding’s a wedding and you’d have to be a curmudgeon to moan about two people plighting their troth (unless you were footing the bill, I suppose).

That said, there seems little doubt that Kanneh-Mason’s appearance was part of a deliberate attempt to diversify the occasion. And that speaks to the world Kanneh-Mason finds himself in now.

Because the truth is he’s a handsome, talented young black man who will look out into an audience of classical music lovers and see a sea of white faces. That needs to change, doesn’t it, Sheku?

“Yeah … Well, yeah. I would, of course, like there to be much more diversity in classical music.”

The question is why is it taking so long? Access, he suggests. “There’s so much great music happening now. The only thing that needs to change, really, is allowing people to hear it, especially young people in schools.”

Ah well that is very much a live issue and he’s talked about the need for music in schools before. The other thing that will help, I suggest, is young black kids seeing someone like him on the TV.

“I really hope so, yes.”

Sheku Kanneh-Mason loves football (he plays midfield), is an enthusiastic table tennis player and is currently binging on Peaky Blinders. The thing that makes him happy, he says, is sleep. “I’m very good at sleeping anywhere.”

So, he does have a life outwith music, then? “Yes, definitely. But having said that, a lot of music comes into life and a lot of life comes into music. There’s not a clean way to separate the two, I think.”

Sheku Kanneh-Mason wants to spend the rest of his life playing music to anyone who will listen to him anywhere in the world. “That’s what I enjoy most doing.”

And in the end that’s all you really need to know. When it comes down to it, whatever question you might want to ask Sheku Kanneh-Mason, the answer will always be music.

Sheku Kanneh-Mason will be performing at the Usher Hall on August 17 with the City of Birmingham Symphony Orchestra conducted by Ludovic Morlot.