20Release of part of security

20 Release of part of security (1) Where any property is held by a trustee by way of security and the trustee has power under this Act or otherwise to invest on mortgage and to vary investments, the trustee— (a) may release part of the property from the mortgage, whether any part of the mortgage debt is repaid or not, provided that the unreleased part of the property would, at the time, be a proper investment in all respects for the amount remaining unpaid; and (b) may, on a sale by the mortgagor of part of the mortgaged property and on the receipt by the trustee of the whole of the purchase money for the part after deduction of the expenses of the sale, release such part from the mortgage. (2) A subsequent purchaser of the released part of the property, or the registrar-general, shall not be concerned to inquire whether the release was authorised by this section.