A previously ''lost'' guitar used by late music legend Prince on his 'Purple Rain' tour is expected to fetch £1 million at auction.

The custom electric blue instrument was one of four ''cloud'' guitars created just for the 'Raspberry Beret' hitmaker's iconic jaunt in 1984 and 1985 in support of his seminal sixth studio album of the same name.

It had disappeared in the 90s, but was finally found last year.

It's tipped to sell for the mega-sum as LA-based auctioneer Julien's carried out a CAT scan on the guitar and it revealed the repairs made to it matched.

Before becoming a striking electric blue shade, it had been white, peach, light blue and yellow.

The auction takes place on June 19, and the sky is the limit for how much it could fetch.

Julien's Martin Nolan said: ''The owners of the other three Cloud guitars won't be selling soon so this opportunity may never come up again.

''There is no ceiling to how well it could do.''

As for the whereabouts of the other three cloud guitars, one was handed out as a prize in a competition, one is privately owned and the other sits in Smithsonian Museum in New York.

A huge number of memorabilia belonging to the 'When Doves Cry' hitmaker has gone under the hammer since his passing at the age of 57 in April 2016.

Prince's yellow high-heeled boots were sold for over $75,000 and were among 200 items auctioned off in 2018.

The custom-made boots were worn by the star during his 1987 'Sign o' the Times' tour, and fetched a whopping $75,147.

Included with boots was a letter of authenticity from the owner of Recordmecca and a former Executive Vice President of Warner Bros. Records, Jeff Gold, who worked alongside the flamboyant star during the 90s, particularly on the records, 'Diamonds & Pearls,' 'Love Symbol,' and 'The Hits/The B-Sides.'

The note read: ''This letter is to authenticate a pair of custom made yellow fabric high heel shoes owned and worn onstage and during photo shoots by Prince. Numerous photographs show Prince wearing identical shoes on stage, and these shoes exhibit wear consistent with Prince's exuberant stage performances ...These shoes were acquired via a former Paisley Park employee.

''Prince wore these boots during the 'Sign o' the Times' tour in 1987, a 34-show concert series that toured exclusively in Europe. In addition to giving the diminutive performer extra height while on stage, these highly stylish boots are in keeping with Prince's trademark flair and innovative gender-fluid style - a brilliant, museum-quality pair of stage-worn boots from the legendary entertainer. (sic)''

Also in the auction was Prince's 1980 Rick James Tour all-access backstage pass which sold for $60,366, as well as an advance pressing of 'Camille', Prince's unreleased 1986 album, which fetched an impressive $58,786.

Handwritten changes to the screenplay for the 'Purple Rain' movie were expected to fetch $12,000 when the auction was announced, but the highest bidder eventually forked out $51,322 for the exclusive item.