Lennon collar for sale in Beatles auction

If you didn't spot it on the cover of the Beatles' Sergeant Pepper album, then there was no way you could miss John Lennon's leather collar on the front of his debut album with Yoko Ono. It was the only thing he was wearing.

The collar, one of the most important items of Beatles memorabilia to have come on to the market in at least a decade, is estimated to make up to £15,000 when it goes on sale at Christie's on 5 May.

But it is not the only highlight of the sale. A custom-made Vox Kensington guitar used by Lennon and George Harrison during Beatles rehearsals is expected to make up to £120,000.

Adozen or so lots are being sold by Alexis Mardis, known as Magic Alex, a Greek engineer and a controversial figure in the Beatles story who was arguably Lennon's closest friend outside the band. An anonymous source is selling a signed copy of the Beatles' first contract, signed in October 1962 by Brian Epstein - the Beatles' manager - the four members of the band and the fathers of George Harrison and Paul McCartney, as both were under 21 at the time and considered minors. It is estimated to fetch anything up to £35,000.

Sarah Hodgson, the head of Christie's pop department, said the growth of interest in pop history made it difficult to gauge likely sale prices. "These are very significant items, the most significant of any rock and pop memorabilia for a very long time," she said.

Mr Mardis's connection with the Beatles made those lots particularly special, she added. He was the head of electronics at the Apple business formed by the band, and among his items on sale are drawings by Lennon, including one made in Paris while allegedly under the influence of LSD. He had met Lennon in 1966.

Some fans blame him for failing to provide the hi-tech recording studio he promised for the Let It Be project.

Christie's said Mr Mardis did not want to discuss his decision to sell the items.