Some jewellery historians believe it features gems from infamous piece at centre of Marie Antoinette scandal

An antique diamond necklace worn at Queen Elizabeth II’s coronation and may be linked to a French scandal involving Marie Antoinette is expected to fetch more than £1m at auction.

The necklace, made of 300 carats, was also worn to King George VI’s coronation by members of the Marquess of Anglesey family, who owned the diamonds until the 1960s when they sold them.