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It is thought to be a record for Knox jewellery – surpassing the gold and turquoise necklace sold at Sotheby’s New York in April 1999 for $32,473 (£19,550) included premium.

The necklace, comes in its original case signed to the silk Liberty & Co Ltd, Regent Street, London, and a sketch for the design appears in the Liberty Sketch Book numbered 8021.

Knox specialist Stephen Martin has requested an image of its sinuous lines for a new edition of his book on the designer.

Its impeccable design credentials were matched by its provenance. It came for sale from the family of the Liberal Party politician Hilda Runciman (née Stevenson), Viscountess Runciman of Doxford (1869-1956).

College Gift

Born in Westoe, Co Durham, the daughter of a Liberal MP for South Shields, Hilda was educated at Girton College, Cambridge, where she gained a first in history.

By repute this daring necklace, fashioned in the Celtic revival style, was given to her by the college in appreciation of her fundraising endeavours.

It was a fitting gift for a woman at the vanguard of social change. In the 1920s, she sat on the executive committee of the Women’s National Liberal Federation, chaired the Westminster Housing Association, and was a founder of the Westminster Housing Trust.

She became an MP in her own right in 1928, when she was elected as member for St Ives.

The buyer, who bid many times the £5000-7000 estimate at the auction on December 10, was a private collector.

The buyer’s premium was 20%