The Housing (Right to Buy) (Designated Regions) Order 1980
Where a dwelling-house disposed of in pursuance of Chapter I of Part I of the Housing Act 1980 is situated in a National Park, an area designated under section 87 of the National Parks and Access to the Countryside Act 1949 as an area of outstanding natural beauty or an area designated by order of the Secretary of State as a rural area, the conveyance or grant effecting that disposal may contain a covenant limiting the freedom of the purchaser and his successors in title to dispose of the dwelling-house by conveying the freehold or assigning the lease, or granting certain kinds of lease or sub-lease other than with the consent of the landlord.