The theft took place on the night of July 19 and the thief is believed to have used a ladder and glass cutters to enter the house, before breaking into two display cabinets.
A similar theft also took place at another country house in East Sussex only four nights later.
Detectives said the thefts could well be connected. Anyone with information should contact New Haven CID on 01273 665639.
• Police are also trying to trace the whereabouts of some valuable pieces of jewellery which were stolen in a violent attack on a woman in West London. The items taken included a solitaire diamond ring claw set in a vintage platinum setting from 1930-1950 and with a retail value of over £18,000. Anyone with information should contact Notting Hill police station on 020 8246 0234. The crime reference number is 5612574.
