The former BBC young musician of the year tells Michael White about the price of success and returning to his roots with the amateur Haydn Chamber Orchestra.

Nothing makes a concert quite so memorable as a disaster – especially one where the disaster turns to triumph. So it’s not surprising that of all the BBC Young Musician finals on TV since the competition launched in 1978, the one people recall is the nail-biter from 2000 when Guy Johnston broke a string in the middle of Shostakovich’s1st Cello Concerto.

With incredible sang-froid for an 18yr-old under pressure, Johnston stopped, replaced the string, and carried on to take first prize – which also proved the first step in an international career that has him playing solo dates with major orchestras.

But next Saturday he temporarily steps down from all that, to reconnect with his past – appearing with the largely amateur Haydn Chamber Orchestra for a charity concert at St Michael’s Highgate in support of Noah’s Ark Children’s Hospice and The Harington Scheme.

He’s playing one of the core-repertoire cello concertos, the Dvorak. And his connection is his father has been principal clarinet in the orchestra since 1994. In past decades he’s regularly worked with HCO to get his fingers round new repertory. And it was with HCO that he prepared the Shostakovich that won him the BBC prize – though whether it prepared him for the snapping string is another matter.

“They’re an amazing group of people”, he explained to me over a Hampstead tea last week, “made up of doctors, lawyers, teachers, business-people passionate about the concerts they perform and doing it with so much energy and love it’s humbling.

“I’ve worked with them a lot – on the Elgar concerto, the Saint-Saens, and the Britten Cello Symphony. It’s always been a good experience, which is why I asked them last year to come and play in the festival I run at Hatfield House every September. They did the Mozart Requiem with King’s, Cambridge Choir, and it was fantastic. So playing the Dvorak with them will be a pleasure. And it’s fortuitous for me because I’m also about to do the Dvorak with the NHK orchestra in Tokyo in March, so this will help me get back under the skin of the piece”.

Pairing the HCO with King’s Choir was no accident, because King’s was where Johnston’s musical life began, as a boy chorister. You may have seen him back there in the TV version of the famous Cambridge carol service that went out last Christmas Eve – not singing but accompanying the voices in a specially commissioned piece for choir and cello.

He enjoys working with singers, and the choral repertoire at large. And he tells me it was almost accidental that he gave up singing for the cello.

“In a way it could have been any one of a number of instruments because my parents ran a music shop in Harpenden where I grew up, and as they sold just about everything you’d find in an orchestra I used to try all these things out.

“But somehow the cello was always there. I think it found me more than I found it. And I’m very glad that the cello I play these days found its way to me because it’s special: a David Tecchler made in 1714. As it’s just passed its 300th birthday I’ve been commissioning new pieces to celebrate the event – one of them by David Matthews which is due to premiere this year in Rome, where Tecchler worked and where the cello came from”.

Other notable events in Johnston’s diary include a major Prom performance, various recordings, and the premiere of a new completion of Herbert Howells’ cello concerto in the Cheltenham Festival, as well as the tour of Japan. But in between he’ll doubtless be keeping an eye on the fact that 2016 brings a new round of the BBC Young Musician competition, with the finals televised next month.

I wondered if each new tranche of young super-talents hoping for careers left him nostalgic for his own experience of early stardom. His response was cautious.

“I can see the pros and cons. Of course it’s an incredible experience to which I owe a lot. But to be growing as an artist in those bright lights is a hard thing. You’re suddenly thrust into a professional environment, learning huge amounts of repertoire in a short time and under serious pressure. So as well as being an opportunity, it can be a burden. And for me it was a bumpy ride.

“Since then, I’ve been a judge of the competition – I was on the panel when the cellist Laura van der Heijden won in 2012 – so I can’t be too critical. But I have in the back of my mind that Laura was just 15 when she had that to deal with. And I do hope she’s going to be OK”.

Johnston’s own route to OK-ness has occasionally involved taking time out from being a soloist, and accepting dates as guest-leader of the cello section in orchestras like the Concertgebouw – “which I love because it gives you an entirely different perspective on repertoire I wouldn’t otherwise play. Last summer I did Beethoven’s 6th Symphony in the Proms with the Aurora orchestra, and we did it from memory. No scores. Which meant we really had to get inside the piece”.

But playing upfront in those bright lights is essentially what he’s about. And having learned the hard way, he can deal with all eventualities. I’d lay good money that he turns up at Highgate with at least one set of spare strings in his pocket.

Guy Johnston plays Dvorak with Haydn Chamber Orchestra, conductor Robin O’Neill,7.30pm, Sat 6th, St Michael’s Highgate. Details: hco.org.uk