It was a Scottish luxury brand, much favoured by Hollywood icon Marilyn Monroe.

And now one of the late film star’s cardigans by MacMillan of Thornielee is set to fetch up to £10,000 at auction.

The cashmere garment was created in the 1950s by the small knitwear firm based in the village of Innerleithen, in Peeblesshire.

The firm, which ceased trading decades ago, made the cardigan for sale at upmarket New York department store, Jay Thorpe.

It was there that it was purchased by Monroe and became one of the favourites in her personal wardrobe collection.

Described as a ‘grey butterfly cardigan’, the item is being sold as part of U.S.-based Heritage Auctions’ ‘Marilyn Monroe Unfiltered’ sale and has been given an estimate of £10,000.

The actress was pictured wearing the item with her arm around her friend Hedda Rosten in a photograph from 1956, while the two were spending time in England during Monroe’s filming of The Prince and the Showgirl with Sir Laurence Olivier.

A description of the lot reads: ‘Marilyn Monroe Personal Grey Butterfly Cardigan. Vintage original light grey cashmere cardigan sweater with delicate butterfly motif from Marilyn Monroe’s personal wardrobe collection, ca. 1955-1962.

‘Crafted from lightweight pure cashmere with long sleeves and a shawl neckline, featuring crème-colored contrast buttonholes and crème and grey embroidered butterfly motifs across the front, back, and both sleeves, creating a delicately feminine design.

‘Retaining internal maker’s label reading, ‘MacMillian of Thornielee/Scotland/100 per cent Pure Cashmere /Made Expressly for Jay Thorpe.’

Bidding for the cardigan began on Monday on the 100th anniversary of Monroe’s birth.

The auction, which also includes letters, private notes and poetry, is described as ‘one of the most intimate and consequential Monroe archives ever to reach the public’.

All the lots in the collection come from the estate of Norman and Hedda Rosten, who were close friends of Monroe.

Joe Maddalena, Executive Vice President of Heritage Auctions, said: ‘Marilyn Monroe remains one of the most enduring and influential figures in American popular culture.

‘While her image and story have been revisited time and again, opportunities to encounter her in such an unfiltered way are exceedingly rare.

‘This is a remarkable archive of primary material that offers fresh insight into her inner world and a true once-in-a-lifetime opportunity for collectors, scholars and admirers alike.’

Previously, an off-white cashmere short-sleeved crew neck sweater by the same firm worn by Monroe – whose real name was Norma Jeane Mortenson and died aged 36 in 1962 – sold for around £7,000, almost five times the top estimate.