5An undertaking by the landlord in the event of damage by fire to any building comprised in the holding to reinstate or replace the building if its reinstatement or replacement is required for the fulfilment of his responsibilities to manage the holding in accordance with the rules of good estate management, and (except where the interest of the landlord is held for the purposes of a government department or a person representing Her Majesty under section 79 of this Act is deemed to be the landlord, or where the landlord has made provision approved by the Secretary of State for defraying the cost of any such reinstatement or replacement) an undertaking by the landlord to insure to their full value all such buildings against damage by fire.