My family has a piano. Its keys are weathered from touch. It has tiny marks on the top right corner where my dad used to gnaw at the wood with his baby teeth.

I always knew this instrument to be special. It felt out of place in our otherwise modest family home (none of my friends had a battle-scarred baby grand in their living rooms, that’s for sure).

My dad told me it had been in our family since 1905, and it was a miracle it was still in our possession and sounding beautiful. Its most prodigious player was his father, Stephen de Bastion, or Istvan Bastyai Holtzer, as his name had been in another lifetime. I never knew my grandfather, who died shortly after I was born. The things I was told about him painted an enigmatic picture: he found success as a pianist in his native Hungary before the war. I knew that he survived a concentration camp. There was a story about him enduring a lonesome walk through Russia.

And I knew – the evidence was right in front of me – that his piano had somehow survived the war as well.

My dad, who taught me to play on our piano and instilled me with an insatiable love of music, died in 2019. The loss left me with a longing for connection. I wanted to know more about the stories our piano had to tell. The opportunity presented itself to write a book about my grandfather and his instrument. It felt, as my ancestors would have called it, beshert (inevitable).

That book, The Piano Player of Budapest, is being published this week, alongside an album in which I have restored, re-recorded and reimagined my grandfather’s music.

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Going through my dad’s things after his death, my sister and I uncovered a treasure trove of memorabilia and documents from my grandfather’s life. Amid photo albums and letters, we found more unusual keepsakes, such as stacks of handwritten sheet music, concert pamphlets and original film scripts from the 1930s, as well as boxes of ageing cassette tapes.

It was strange to know they had been there all along – I had no idea I was growing up among these precious remnants of a bygone era.

I was aware that Stephen recorded his war story late in life, but I had never felt ready to hear it, to be confronted with the details of what happened to him and my family during the Holocaust.

I was nervous when I pressed play. But as I sat listening to my grandfather tell his story in his own words, I ­realised he was sharing far more than the tale of his persecution. Stephen took me by the hand and walked me through his entire life – from his privileged upbringing (his parents ran a successful textile company) to his youthful escapades, outlining his hedonistic, cocktail-swilling, womanising lifestyle in roaring Budapest in great detail. Talented and stubborn, he forged his own way, building a bright future in music that was ultimately never meant to be.

It felt as though I had reached through time – I was getting to know my grandfather posthumously. His charm, his sense of humour, his boisterousness – it was all there in his inflections, in what he chose to highlight and to omit, in the long pauses he’d sometimes leave for emphasis or to brace himself before sharing something difficult.

Throughout the 1930s, Stephen composed feverishly, performing in hotels, bars and theatres across Hungary and Switzerland, as well as scoring music for Hungarian films. It was all going so well until his career – his life – was brought to a screeching halt by war.

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In October 1942, Stephen was sent to the front as a forced labourer and suffered horrific abuse. When his group was abandoned as the Soviet army broke through, he fled and made his way home on foot. Out of the 1,070 Jewish men sent out, he was one of eight who returned – only to be deported to the Mauthausen and subsequently Gunskirchen concentration camps, where he clung to life for more than a year until liberation. His story teaches many lessons. It is a painful reminder of what humans are capable of when we succumb to scapegoating and othering. The slow but steady erosion of my family’s rights and the propaganda machine that made millions of silent bystanders complicit in crimes against humanity should serve as a warning. When we lose our empathy, we lose everything.

Every Holocaust survival story is miraculous. My grandfather’s is so full of inconceivable twists of fate, it defies belief. Improbably, he landed his biggest hit in 1946, when Hungary’s famous jazz singer Kato Fenjesh recorded his song Emlegszel Meg (Do You Remember) and it became a zeitgeist anthem.

Despite the success, Stephen no longer felt safe in Hungary. With the help of refugee charities, my grandparents (along with Stephen’s piano) started a new life in Stratford-upon-Avon. My grandfather wasn’t able to continue his music career in postwar Britain – with xenophobic attitudes, assimilation was difficult. But he never stopped composing, playing and recording his music.

Writing the book, I would listen to those recordings. It dawned on me that I had an opportunity to bring his music back to life. I teamed up with guitarist/producer Simon Tong, a member of the Verve who has played with Damon Albarn, to digitise the tapes and create a new album based on Stephen’s music. Together with pianist Xenia Pestova Bennett, we travelled to my family home to record some of Stephen’s compositions on his piano, using his original sheet music. It’s hard to convey just how powerful and moving a moment this was – to hear the piano sing out Stephen’s compositions once more. Generational healing through music.

Collaborating with my ­grandfather through space and time has been a magical ­experience. Yesterday I performed his music at my book and album launch at the Royal Albert Hall – the first public performance of his music since 1957. I’d like to think Stephen would be delighted to have his comeback at such a prestigious venue. To share his story and music is an honour. It is time for Stephen to step back into the spotlight.

• The Piano Player of Budapest (Little Brown) will be out 6 June and the album, Songs From The Piano Player of Budapest, 21 June