A negative from Marilyn Monroe's first ever professional photoshoot, when she was 20, is going under the hammer in Devizes.

At the time it was taken Monroe was the unknown Norma Jeane Baker, a factory girl dreaming of becoming a model.

Aged just 20, she was posing for her first professional photoshoot and almost 70 years later, a negative from that session will go under the hammer at a Wiltshire auction house.

The negative - and most crucially, the copyright to the image - will be sold on Saturday, September 20, and is estimated to fetch between £5,000 and £8,000.

In 1946, Norma Jeane was married and working at a munitions factory when a passing military government photographer told her she could be a model, so she approached a Hollywood modelling agency, Blue Book.

Young aspiring photographer Joseph Jasgur was assigned to get her first portfolio and took her to Zuma beach in Malibu for a few pictures, which were later presented to Ben Lyon, casting director at 20th Century Fox.

They were the pictures that would not only make Jasgur famous but create a star in Norma Jeane, who later dazzled Hollywood and sparked international headlines.

"With aspirations of becoming a model, she joined Hollywood's Blue Book Model Agency," said Andrew Aldridge, from Henry Aldridge and Sons, in Devizes.

"On March 6, 1946, Joseph Jasgur received a call from Emmeline Snively, head of Blue Book. Snively asked Jasgur to take a few test shots of an aspiring young model.

"He first photographed her on a small street in West Hollywood behind Beverly Boulevard and over the next few weeks he photographed her on top of Don Lee Towers, above the Hollywood sign and at Zuma Beach, where this image was taken.

"This photo offers a unique glimpse of the young girl who was later to become the global phenomena that was Marilyn Monroe.

"It is exceptionally rare for photos of this type to come to auction, however the true value in this image lies in the fact that it is sold with its own copyright to reproduce and distribute the image as the winning bidder wishes."

The auction house, which has a reputation for selling anything connected to the doomed Titanic liner, is now branching out into celebrity memorabilia.

And the owner of the photograph, an American, passed up the opportunity to sell it in the US, preferring Devizes.