Heirlooms worth nearly £700,000, including a diamond ring given by Charles II to his mistress, have been stolen in a raid at one of Britain's most treasured stately homes.
Detectives have made a nationwide appeal following the break-in at 17th Century Goodwood House near Chichester, West Sussex, in the early hours of Wednesday morning.
Lord March - the founder of the Goodwood Festival of Speed - and his wife Lady March have been left "devastated" at the theft of "irreplaceable" items, police said.
Heirlooms, including an 1820 diamond tiara worth nearly £400,000, diamond necklaces and several luxury watches, including antique Rolex and Girard Perregaux timepieces, were stolen.
Other items taken included an emerald intaglio and diamond ring from 1800, engraved with the Duchess's coronet and monogram CL for Louise de Keroualle, mistress of Charles II.
More than 40 items were stolen including emerald, diamond and sapphire rings, earrings, bracelets and necklaces, Sussex Police said as they appealed for information.
Detective Inspector Till Sanderson said: "The theft of these beautiful and treasured items have left the victims Lord and Lady March devastated at their loss."
Investigators were working with auction houses, stately homes, dealers and those with specialist knowledge to try to trace the heirlooms.
A 26-year-old man from Hampshire has been arrested in connection with the incident and was in police custody facing questioning.