The Registrar-General shall, for the purpose of a sale authorised by section 58, register a transfer executed by a mortgagee, chargee or covenant chargee in the approved form and, upon that registration, the estate or interest of the mortgagor, charger or covenant charger in the land comprised in the transfer shall pass to and be vested in the transferee, freed and discharged from all liability on account of the mortgage, charge or covenant charge, or of any mortgage, charge or covenant charge registered subsequent thereto.