(1) Where an approved mortgagee assigns the mortgage debt secured under an approved mortgage and conveys the mortgaged property to another person, the Authority's liability under the guarantee entered into in respect of the repayment of such mortgage debt shall cease and the guarantee shall be void, unless—
(a) the assignment of such debt and the conveyance of the mortgaged property were made to an approved mortgagee; or
(b) the person to whom the assignment and conveyance were made permits the mortgage to be serviced by the Authority or, subject to such terms as the Authority may think fit, by an approved mortgagee.
(2) Regulation 20 shall apply in the case of any such assignment and conveyance as if the expression “the mortgagee” contained therein included a reference to the assignee of the interest of the mortgagee.