So palpable is her pain, she could be talking about a lost child, a departed parent, or even a former lover.

‘The truth is I try not to think about it too much,’ Min-Jin Kym admits, becoming upset even at the memory. ‘You can drive yourself mad. It’s like if the love of your life is with someone else. You can’t bear to think about it.’

But the 38-year-old isn’t referring to a person. She’s talking about a musical instrument — her £1.2 million Stradivarius violin, stolen while she picked up a coffee and a sandwich in a Pret A Manger seven years ago.

The extent of Min Kym’s distress may be hard to comprehend for non-musicians, but for the former child prodigy who was born in South Korea but moved to London as a young child, the loss was catastrophic.

Min-Jin Kym's life fell apart when her 315-year-old Stradivarius was stolen from a Pret A Manger in Manchester in 2010

The anorexia she suffered as a teenager reared its head again, her relationship with a fellow musician crumbled and — overnight — her glittering career, one that had seen her play at the Royal Albert Hall and secure a prestigious recording contract, was over. The loss of her violin caused her to question every aspect of her life. At one point she even consulted a medium in an attempt to locate it. She became, as she puts it, ‘unstrung’.

‘The shock and grief just stopped me in my tracks,’ Min recalls. ‘I couldn’t get out of bed, let alone think of playing. I couldn’t even listen to music.’

The story of Min’s relationship with her Stradivarius and what happened after it was stolen is utterly compelling. While she and the violin were eventually reunited, there was no happy ending.

Her memoir, Gone, is part thriller (the details of how police launched an international investigation is worthy of a crime novel) and part love story. It also offers a dark glimpse into the relentless world of the child prodigy.

Min’s musical journey started at the age of six when she moved to London with her parents. They weren’t a musical family (her father’s job, working as an engineer for Daewoo, had brought them to the UK), but she tagged along to her big sister’s piano lessons and decided she would rather play the violin.

By the end of the first lesson, the teacher told her mother that they were dealing with a child prodigy. Within three months she had passed her Grade 4 exam (with the highest marks in the country) and at seven became the youngest pupil to be admitted to the prestigious Purcell School (the normal entrance age is nine) in Hertfordshire.

By 11 she had won an international music competition, and started playing professionally — all over the world — the following year. At 15, she became the youngest person to be awarded a foundation scholarship at the Royal College of Music.

She has only recently questioned how healthy this life was. She recalls being on tour in Spain, aged 12. ‘I was skipping along, as kids do, but my manager shouted “Min, look, you are on that poster up there. There are people coming to pay to see you. They will recognise your face. You cannot be acting like a child”. That became the voice in my head. People expected me to act in a certain way.’

This expectation began taking its toll. Min thinks her anorexia started when an older girl, seeing her eat a bowl of pasta, asked: ‘Aren’t you worried about getting fat? Nobody wants to see a fat performer.’

By 14 she would eat only every other day, revelling in how thin her arms looked as she held up her violin. Shockingly, in her book she claims the school knew and did nothing. ‘Don’t let people know you are ill,’ a piano tutor told her. ‘It will kill your career.’

By 11, Min had won an international music competition, and started playing professionally the following year

Her mother was asked by the school to ‘keep an eye on her’, but Min says: ‘She was scared and out of her depth. Anorexia didn’t exist in her world.’

She believes now that it suited everyone to brush the situation under the carpet. ‘My parents, my tutors, my managers, my agents, they all wanted me to remain a child — it was easier that way.

‘They didn’t want puberty or teenage angst. They wanted the little girl with the winning smile. I didn’t have the energy to fight back.’

The one constant in Min’s life was music. Many child prodigies burn out, but while she did scale back her recording work when she went to music college, she came back. By her twenties she seemed more robust, healthier, more focused.

Finding her Stradivarius when she was 21 was the icing on the cake. She had known for some time that to reach the very top, she would need a top-class instrument, and had asked a dealer to keep an eye out.

One day, he called with news of a Stradivarius. Made in 1696 it was one of only 449 in the world. The first time she played it, she says she ‘felt like Cinderella’. Thus began possibly the most important relationship in her life. ‘It was like an addiction,’ she agrees. ‘A good addiction.’

The fact that she could afford to buy the instrument — at a cost, then, of £450,000 — seems incredible, but she points out that she had been working since 12, and her parents had invested the money wisely. She had also remortgaged her London flat, and was living ‘in a shoebox’.

‘The violin was my priority. It WAS my home, in a sense. It was my life.

‘Wherever I was in the world, it was with me. The relationship you have with an instrument like that is difficult to explain but every time you play it, it absorbs a part of you.

‘All your emotion seeps in there. It was as much a part of me as my leg or my arm.’

Then came the fateful day in 2010, as she prepared to tour to promote a recording of a Brahms Violin Concerto. By now the instrument was valued at £1.2 million — though it was still only insured for £750,000.

She and her boyfriend Matt, a cellist she had been seeing for only a few months, were travelling to Manchester for an event. She remembers they argued while trying to find space in the tiny Euston station cafe to accommodate two cases, a cello and her Strad — complete with £65,000 worth of bows in the case.

She gets agitated at how the theft was reported in the media, furious that the world imagined this precious instrument had been discarded on the floor, carelessly. ‘I always guarded it with my life. I used to wrap the strap around my foot. It was NEVER away from me.’

At 21, Min found the Stradivarius, made in 1696. It was one of only 449 in the world. She bought it for £450,000 and said the first time she played it, she ‘felt like Cinderella’

Except that on this day it was. Matt, seeing that she was struggling to find any comfort in the crowded cafe, asked her to pass the violin to him. ‘I said “no way!” she recalls.

This passage in the book is frantic. ‘He is insistent. We argue back and forth, where he wants it, where it should go. Finally, I relent, following the pattern of acceptance that is our default position — the pattern of acceptance I have always fallen into, Min giving way, Min obeying’.

She insists that she followed up the handover of the violin by ‘telling Matt to take care of it’.

Both were unaware that three men were looking around Pret, hunting for prey. CCTV footage would later show the men training their focus on another unsuspecting woman’s handbag. But then they changed their minds. Neither Min nor Matt saw the hand snaking out to take the violin case. Although it was right beside Matt, the pair — tired and clearly distracted — simply did not see that it was gone.

She says she still has nightmares about what followed. ‘I remembering shouting “it’s gone, gone, GONE” and the guy serving trying to calm me down, thinking I’d had a handbag snatched. Then I went to pieces. I still can’t bear to think about it.’

For the next three years Min struggled to cope with the loss. Her relationship with Matt disintegrated. Did she blame him? ‘I think blame is too loaded a word,’ she says.

‘At the time, yes, I did shout “how could you?”. He was in charge of my violin. It was stolen under his care, but it was stolen so that’s not a passive act.’ But she admits their relationship ‘wasn’t strong enough to withstand the test’.

Her management team arranged for other top-class violins to be made available to her. But she just couldn’t play them. ‘Someone, meaning to be kind, did say “yours is not the only violin in the world, Min”, But it was to me. If it had been my child, would people have expected me to accept ANOTHER one? Just as good!’. She shakes her head. ‘I think only another musician can understand.’

Unable to perform, her record deal ended. She couldn’t sleep or eat. The dark spectre of her anorexia returned. ‘Whenever I’m stressed, I stop eating,’ she has said since. ‘It’s not a control thing, it’s the anxiety, but because I’m an adult now I can force myself to have something light. But as a child I was so overwhelmed.’

No aspect of her life was unaffected. ‘The loss of my violin forced me to look at my life,’ she tells me. ‘Suddenly the prop to my whole life was gone and I realised I’d built almost my whole life on sand. Did I have a voice outside music? Did I exist?’

A year after the theft, justice was officially served. Police realised they were dealing with an opportunistic attack rather than a targeted theft, and CCTV footage eventually led them to the gang.

John Maughan (pictured), 30, who stole the violin, was a serial offender with 123 previous offences to his name

John Maughan, 30, was a serial offender with 123 previous offences to his name. In April 2011 he was jailed for four and a half years for stealing the violin, later reduced on appeal to three and a half. His two accomplices, aged 16 and 15, also admitted theft. The older youth was given ten months’ detention, while the younger was referred to a youth court for sentencing.

Where was the instrument though? That was still a mystery.

Three years after her Stradivarius had been stolen, and after she had even consulted a medium to locate it, Min had — in her words — moved ‘into the acceptance part of the bereavement process’.

The insurance company had paid out, but she had to pay capital gains tax on the £750,000, leaving her with only a fraction of what the violin was worth. Once debts were consolidated (remember her record deal was now gone, and she had not been earning) and another violin was purchased, she had very little left.

Then, in July 2013, just after she started to play again, the police investigation had produced a breakthrough. She still doesn’t know the details, but the violin was found, in storage, in a warehouse in the Midlands.

If this extraordinary story were a Hollywood film that’s where the curtain would come down, with Min having been reunited with her precious violin. In reality the ending was bittersweet.

She did get to play it again, and almost breaks down today at the description of what that felt like.

‘It was exactly the same. It even still had the strings I put on it,’ she remembers. ‘I was home.’

But it wasn’t hers any more. The minute she accepted the insurers’ cheque, it belonged to them.

Her desperate battle to raise the money to buy it back came to nothing. The violin was sold at auction for £1.3m, and she had to let it go. For ever.

Clearly nothing will ever compare. She is withering about ‘her’ Strad’s new owner (part of a consortium), who does play but not to the level she thinks the violin demands (‘I don’t think he has the means for that, the hand, the eye, the ability’) and her book contains a passionate rant on how ‘violins like my Strad are not bought to play as they once were.

‘They sit in safes. They do not earn their keep in concert halls. They earn their keep in the dark.’

What of Min? She is relaunching her career, determined that writing down her story has helped her come to terms with what happened. She holds her ‘new’ violin in a careful embrace and admits she is ‘working on’ the relationship she has with it.

The casual listener will still say she plays like an angel. She shakes her head. ‘It will never be the same.’