A set of rosary beads said to have been carried by Mary Queen of Scots to her execution are among "irreplaceable" treasures missing after a late-night raid at Arundel Castle.
According to Sussex Police, the treasures are among gold and silver items worth in excess of £1million.
At 10.30pm on Friday 21 May Castle staff were alerted of a break in after a burglar alarm had sounded.
What officers and some historians calleld "items of great historical significance" were found to be missing.
These include the Gold Rosary Beads carried by Mary Queen of Scots at her execution in 1587, several coronation cups given by the Sovereign to the Earl Marshal of the day, and other gold and silver treasures.
Officers said that the rosary is of little intrinsic value as metal, but as piece of the Howard family history and the nation’s heritage, it is irreplaceable.
The items were taken by force from a display cabinet along the public route.
Images of the cabinet as a whole, a few days before the burglary, show the items taken along with other treasures not stolen.
A spokesman for Arundel Castle Trustees said:
"The stolen items have significant monetary value, but as unique artefacts of the Duke of Norfolk’s collection have immeasurably greater and priceless historical importance.
"We therefore urge anyone with information to come forward to the police to assist them in returning these treasures back where they belong.”
Police are examining a 4x4 saloon which was found abandoned and on fire in nearby Barlavington a short while later, to establish whether it is connected to the burglary.
Detective Constable Molly O'Malley of Chichester CID said:
"If you were in Arundel on Friday evening and saw any suspicious activity around the area of the Castle, please contact us either online or by calling 101, quoting Operation Deuce.
"In addition, the castle only re-opened to visitors on Tuesday 18 May so if you were visiting during the past few days do you on reflection recall anyone behaving at all suspiciously?
"If you are offered or hear of anyone offering for sale any of the items stolen, we would also like to hear from you."
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