A greatly expanded slang lexicon for the delinquent droogs of the novel A Clockwork Orange has been unearthed in a vast archive of the work and life of Anthony Burgess held in Manchester, alongside the libretto and score of an unseen opera about Leon Trotsky, and the script for an unmade TV series about Attila the Hun.

In preparation for next year's 50th anniversary of his notorious novel, one of the most controversial modern works in the English language, the small team at the International Anthony Burgess Foundation have been working to organise and catalogue hundreds of papers, letters and original compositions, ready for an influx of international visitors.

The extraordinary resource, which has been left to the foundation by Burgess's widow Liana, is newly housed in a renovated building in a regenerated area of the city and is a bulging testament to the writer's prolific literary and musical talent. Already, gems unearthed in the archive have provided musical material for a series of concerts and for an operatic version of A Clockwork Orange that had its first studio performance at Manchester University last week. A play about the life of Napoleon will have its premiere on BBC Radio next year.

Manchester-born Anthony Burgess, who died in 1993, wrote at least 33 novels, 25 works of non-fiction, two volumes of autobiography, three symphonies, and more than 250 other musical works including a piano concerto, a ballet and stage musicals.

But more is coming to light every day. "Last week we opened up a case and inside we found a piece of music we didn't know about, a pair of driving gloves belonging to Liana and a tape recording for his music The Eyes of New York, which is not transcribed anywhere," said Andrew Biswell, the director of the foundation and Burgess's biographer. "It is a programmatic work which describes a journey around some of his favourite places in the city."

The 1969 screenplay Burgess wrote for Stanley Kubrick was ultimately rejected by the film director, but he did read it before writing his own version. Although Kubrick's violent rendition was critically acclaimed, it was withdrawn from cinemas by the director himself for 27 years until 2001. Now rediscovered in the archive, Burgess' screenplay is laced with a new words from the language, Nadsat, a melding of English and Russian, that the author gave his droogs in the original novel, published in 1962. So now, as well as cult vocabulary such as 'Moloko' for milk, fans also have phrases like "cheested up" for getting clean, or Zemolchy, which is an exclaimation of delight or wonder.

On Wednesday last week, five song lyrics written by the author and set to music by the University of Manchester's Head of Composition, Dr Kevin Malone, were performed for the first time as A Clockwork Operetta on the campus, the place where Burgess graduated in English Literature in 1940.

He had grown up in Harphurey and Moss Side in the care of his aunt, following the death of his mother and sister from influenza, and then lived with his father and a second wife in the city.

The world premiere was performed by all-female ensemble the Ebb Trio, dressed as droogs, at the University's Martin Harris Centre. Dr Malone's music draws on Beethoven, Burgess's musical hero, but also makes reference to the novelist's popular stage version, which was performed by the Royal Shakespeare Company in 1990.

Biswell said many visitors to the foundation are curious to know the author's music sounds and he hopes that a CD will soon be available. Until then, he points to the lyrical music of William Walton, Gustav Holst or Vaughan Williams. The foundation hopes to make grants to writers and musicians who are creating work in the spirit of Burgess.

"I think he was always quite frustrated by the way some people would not take him seriously as a musician because he was known as a writer," said Biswell.

While many critics and pundits have denounced Burgess (including another biographer of the author, Roger Lewis, who called his subject "a definition of hell") for his violent imagination and his supposed prejudice, the Manchester archive will present an unexpectedly varied picture of the pundit and raconteur. Although he was vilified by some for his attitude to feminism, the new archive will prove he kept up a personal correspondence with strong women writers such as Olivia Manning, author of Fortunes of War, Erica Jong, his neighbour in Monaco, and with Angela Carter. He also exchanged appreciative letters with Benny Hill.