The art deco piece was famously worn by Margaret for her 19th birthday photograph taken by celebrated photographer Cecil Beaton in 1949.

It was bought by an undisclosed private bidder for £396,800, including buyer's premium, during the sale at auction firm Dix Noonan Webb's Mayfair saleroom in central London. 

Frances Noble, the company's associate director and head of the jewellery department, said of the sale price: 'It not only reflects the strength of the current auction market but also the overriding importance of provenance.

'Princess Margaret was photographed wearing this bracelet on numerous occasions which certainly added to the appeal of the piece, attracting international interest and extremely competitive bidding - an exceptional result for the vendor.'