18.—(1) Subject to section 17, a decree or an order for, or having the effect of an order for, foreclosure in respect of mortgaged property is chargeable with duty as if it were a conveyance of that property on sale.
(2) The ad valorem stamp duty upon any decree or order under subsection (1) must not exceed the duty on a sum equal to the value of the property to which the decree or order relates, and where the decree or order states that value, such statement is conclusive for the purpose of determining the amount of the duty.
(3) Where ad valorem stamp duty is paid upon any decree or order under subsection (1), any conveyance following upon that decree or order is exempt from the ad valorem stamp duty.