Police are trying to trace a man after a theft from Petworth House in West Sussex.
Officer say he was seen behaving suspiciously at the National Trust property on Wednesday 1 August.
He was seen on CCTV trying to open locked doors before leaving the premises.
He is described as white, in his fifties, of medium height and heavy build, with short grey hair. He was wearing a beige t-shirt with dark trousers and shoes.
Detective Constable Andrea Watts said: "We believe this may be the same man we want to interview about the theft of two valuable plates from Petworth House."
The pair of Japanese porcelain plates with similar designs were stolen on the afternoon of Thursday 9 February. They are 325mm in diameter, white with blue, orange and green decoration, and have gold edges. Each has a distinctive floral pattern of chrysanthemums and peonies behind orange-coloured fencing in the centre. Around the rims of the plates are further floral decorations of irises, lychees and peonies. The plates were marked by hand on the base with the numbers L/PET/C/99.1 and L/PET/C/99.2. These numbers may have been covered or scratched from the glaze.
If you recognise this man or have knowledge of where these plates may be please contact police on 101 quoting serial 1375 of 1 August. You can also call the independent charity Crimestoppers on 0800 555 111.