6.—(1) Any transfer under regulations 12 or 14 (except of retained dwellings which subsequently cease to be retained dwellings) shall be for the amount (which may be a negative amount) determined in the final valuation.
(2) Any other transfer of property under these Regulations shall be for an amount (which may be a negative amount) equal to the price which, on the basis of the assumptions described in regulation 16(3), it would realise if sold on the open market by a willing vendor.