The sister of "fifth Beatle" Stuart Sutcliffe declares he was the "central driving force" behind the band, as she prepares to put his personal possessions up for auction.
Sutcliffe (c) formed the band with Harrison and Lennon
Pauline Sutcliffe has dedicated her life to collecting and writing about her brother, who was one of the original members of the Liverpool group.
Stuart Sutcliffe was a founding member of the Quarrymen, who later became the Beatles, but quit in 1961 before they hit the big time to pursue a career in art.
He died of a brain haemorrhage the following year at the age of 21, but was credited with giving the group its distinctive image.
Miss Sutcliffe has collected masses of memorabilia from his short life, with a large selection going under the hammer at Bonham's auction house on 29 July.
Among Sutcliffe's personal belongings for sale include his birth certificate, which is expected to fetch up to £8,000, and exam certificates from his time at the Liverpool College of Art, where he met John Lennon.
Miss Sutcliffe said: "This sale confirms for me that I haven't spent 40 years of my life in vain.
"You see I always believed Stuart was not only the central force behind The Beatles - but also the member who most influenced their public image, making style statements that still reverberate throughout the world to this day.
"More importantly though he was an artist who chose to put his affiliation with The Beatles to the side in order to pursue his first love - his art."
Other items in the sale include sketches, photographs and letters to his family and girlfriend Astrid Kirchherr, who he lived with in Hamburg, Germany.
The 1993 film Backbeat, starring Stephen Dorff, told the story of Sutcliffe's life.