The site of Yonsea farm was the subject of an archaeological investigation prior to construction works for the Channel Tunnel Rail Link. The location of archaeology associated with a possible earlier medieval moated site was the principal aim of these excavations. The area occupied by the 19th century buildings was not available for archaeological investigation. No archaeological features were found within the walled garden. The southern return of the possible 'moat' was shown to be a substantial feature that at one time contained standing water.