Detectives investigating the theft of more than £700,000 of jewellery at Goodwood House near Chichester have renewed their appeal for witnesses.
The jewellery, including historic heirlooms were taken during the break-in at around 4.30am on Wednesday.
"This was a frightening ordeal and I pay tribute to the courage of Lord and Lady March.
The historic items include:
an 1820 diamond tiara, worth in the region of £400,000
an antique diamond necklace from the first half of the 19th century, worth in the region of £200,000
an emerald intaglio and diamond ring from 1800, engraved with Duchess's coronet and monogram CL for Louise de Keroualle, mistress of Charles II.
"The last 48 hours have been challenging and I would like to thank Sussex Police, my team here at Goodwood and the local and national press for their support. I am pleased to tell you that we are both recovering and entirely focused on providing the police with anything that may help recover the stolen items some of which have such personal significance and others such historical value."
A 26-year-old man from Hampshire has been arrested on suspicion of robbery and has been bailed until February while investigations continue.