Ewa Wyszogrodzka is grateful for the unknown builders who, after discovering a suitcase in the garden of a destroyed house in Warsaw at the end of the second world war, handed it to authorities.

Its contents – pages of musical composition – were placed in the Polish national library for safekeeping, where they lay forgotten for years.

The manuscripts had been buried by Wyszogrodzka’s great-grandfather, the composer Ludomir Różycki, before he fled the war-torn city.

On a recent afternoon, Wyszogrodzka wiped tears from her face as she listened to a Polish virtuoso violinist bring the works to life.

“Listening to the music, it’s like getting to know my great-grandfather for the first time,” said Wyszogrodzka, an economist, sitting in the foyer of the Philharmonic Hall in Szczecin, north-west Poland after a concert of Różycki’s works. “To think, these pieces might have been lost forever.”

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Janusz Wawrowski, considered Poland’s leading classical violinist, spent about a decade reconstructing Różycki’s Violin Concerto – an exuberant, optimistic work comparable to that of George Gershwin or the film composer Erich Wolfgang Korngold, which was never performed in his lifetime – after finding the original orchestral score as well as the basic piano arrangement in two separate archives.

When he realised by what he calls a “happy accident” that they belonged to one and the same Różycki Violin Concerto, he started the complicated task of musically intertwining them.

“I spent years experimenting to get the sound I think Różycki would have wanted,” Wawrowski said. “I changed it to make it more violinistic, more technically complicated – as he was more of a pianist. To me it’s full of the energy and life of Warsaw before the war, and I think he was trying to conjure and convey this positive energy as he wrote it in 1944 in a very dark time, as the artillery of the Nazis rained down on the city.”

As he performed the Violin Concerto with Szczecin’s Symphony Orchestra at the weekend to rave reviews, Wawrowski’s Stradivarius appeared to want to take flight as the musician, dressed in a turquoise silk shirt, lifted and dipped his toes, mastering the many double stops and chords of a piece with hints of everything from ragtime to polonaise. It was, critics said, reminiscent of Stravinsky or Brahms, with whom Różycki in his heyday was often compared.

Piotr Urbański, a musicologist at Poznan University, said it was “rich, clear and brilliant, connecting us with a part of Polish history which was very tough (when it was under the occupation of Nazi Germany) but he used his music to encourage optimism, like a kind of therapy.” At the same time, he said, he believed Różycki hoped the composition, with its patriotic overtones, would help establish him as a national composer of Poland.

Wawrowski has recorded the concerto with London’s Royal Philharmonic Orchestra, under the baton of its principal associate conductor, Grzegorz Nowak, who is Polish. Both men are hoping that the recording, due out next year, will help bring Różycki to a wider audience and put him firmly back at the heart of the Polish classical canon, where he was in the 1920s and 30s alongside the likes of Mieczysław Karłowicz, Grzegorz Fitelberg and Karol Szymanowski, who were collectively referred to as Young Poland.

Facebook Twitter Pinterest Janusz Wawrowski playing with the Royal Philharmonic Orchestra. Photograph: Cezary Aszkiełowicz/Szczecin Philharmonic Symphony Orchestra

“He was one of the most important composers of the first half of the 20th century,” said Urbański, “but he’s unknown to most Poles today. Let’s hope that will now change.”

Różycki studied piano and composition at the Warsaw Conservatory and continued his musical education in Weimar Berlin under the German opera composer Engelbert Humperdinck, where he befriended the likes of Richard Strauss and Giacomo Puccini. His ballet Pan Twardowski was an international success, performed across central and eastern Europe, including more than 800 times in Warsaw.

Wyszogrodzka said family stories about the composer were rare. Her great-grandmother remarried after his death in 1953 and kept many details to herself. “But I do remember my grandmother telling me how he had been interrogated by the Gestapo,” she said.

They had tried to make him sign the so-called Volksliste, a Nazi-party initiative to classify the desirability of inhabitants of the regime’s occupied territories. Różycki refused and so was forced to flee. “There were no USB sticks in those days, so he was forced to put his scores in a suitcase and bury it in the garden,” Wyszogrodzka said. “The family thought they’d have the opportunity to find it after the war, but they never came back, and assumed it had been lost or destroyed.”

At the recent concert, Wawrowski and the orchestra, under the baton of Norbert Twórczyński, also performed Różycki’s Pieta, a work he completed in 1942, the manuscript of which was destroyed in the Warsaw Uprising.

“He had kept a memory of it in his head, so after the war, settled near Katowice, he was able to construct it, with the help of musician friends,” said Wawrowski, who believes there are hundreds of abandoned works waiting to be discovered in Polish archives.

Różycki had also wanted to reconstruct from memory the incomplete Violin Concerto but his violinist friends, whom he might have consulted, were scattered far and wide because of the war. “I’ve sometimes thought I was a substitute for the violinist friend, having that conversation with him but decades apart,” Wawrowski said.