The gold rosary beads carried by Mary Queen of Scots to her execution in 1587 were among historic treasures worth more than 1 million pounds ($1.4 million) stolen in a raid from a castle in the south of England.
Mary, a Roman Catholic, was ousted from the Scottish throne then imprisoned, accused of treason and executed on the orders of her Protestant cousin Elizabeth I of England, a series of events that loom large in the British imagination.
Several coronation cups as well as gold and silver items were also among the loot taken from a display cabinet at Arundel Castle in the county of West Sussex.
Staff were alerted to the break-in on Friday evening and the police arrived within minutes. Officers are examining an abandoned 4x4 car which was discovered on fire soon after the theft.
Sussex police said the rosary was of little value as metal, but was "irreplaceable" as part of the nation's heritage.
"Various items have been stolen of great historical significance," the police said in a statement.
Mary was briefly queen of France. She was later driven out of Scotland by rebellious aristocrats and fled south in 1568 at the age of 25, throwing herself on the mercy of her cousin Elizabeth.
But with many Catholics throughout Europe convinced that she had a better claim to the English throne than the Protestant Elizabeth, Mary was an unwelcome visitor.
She was confined in various English castles and prisons, convicted of plotting against the English queen, condemned to death for treason on charges she denied and finally beheaded.
Andrew Griffith, the member of parliament representing the area where Arundel Castle is located, said: "The whole nation joins our sadness this morning. The theft of these irreplaceable artefacts connecting us to our shared history is a crime against us all."