The Royal Academy of Music has bought the archive of violinist Yehudi Menuhin for £1.2m after striking a deal with the late musician's family.
Yehudi Menuhin's archive will be made available to the public
The extensive archive includes letters from Elgar, Bartok and Albert Einstein and original scores by Mendelssohn.
But The Times reports a condition of the sale is the "discreet" handling of Menuhin's "intimate" correspondence with members of the Royal Family.
The first exhibition of the archive will open in London on 25 March.
The Royal Academy describes the collection as "one of the most valuable and comprehensive collections ever assembled by an individual musician".
The acquisition was made possible by a £1.2m grant from the Foyle Foundation, with an additional £200,000 for its conservation.
Items from the archive will be displayed regularly at the Academy's free "living museum" and research centre, the York Gate Collections, in central London.
The archive includes letters by Edward Elgar (photo by Rita Castle)
But a spokesman for the Academy said none of the royal items - which includes letters to and from the Prince of Wales and the Queen Mother - would be made available to the public.
"The family is personally attached to some items," he said. "They are not particularly important historically but have great sentimental value."
However, he said the public would have access to the "vast majority" of Menuhin's correspondence.
The archive contains important musical manuscripts by many of the composers who worked with Menuhin, including music from his collaborations with Ravi Shankar and Stephane Grappelli.
In addition to detailed correspondence with Edward Elgar, Bela Bartok and Benjamin Britten, the archive includes letters from Albert Einstein and Indian prime minister Jawaharlal Nehru.
There is also an extensive photographic record of Menuhin's life, including images signed by Charlie Chaplin, Jean Sibelius and Arturo Toscanini.
Yehudi Menuhin was one of the foremost violinists of his age
Menuhin, who died in 1999 at the age of 82, was recognised as one of the greatest musical geniuses of the last 100 years.
Born in New York in 1916, he was an astounding musical prodigy who had performed in London, Paris and Berlin by the age of 13.
One of the foremost violinists of his age, Menuhin delighted audiences around the world with his smoothness of tone and the physicality of his performances.
But he was also an educator. In the 1960s he founded the Yehudi Menuhin school for gifted young musicians, where Nigel Kennedy was one of his pupils.
"I really think music is a birthright that belongs to every child," he told the BBC in 1997. "I put it on the same level as breathing air."
He was knighted in 1987 and became a life peer in 1993.
"Yehudi had a particular affection for the Academy, and his last public master classes were given here," said principal Professor Curtis Price.
"I am particularly pleased that his archive will now be made available to the public and will not be dispersed worldwide."