(1) For the purposes of this Act -

(a) any payments or other rewards received by a person at any time (whether before or after the commencement of section 4 of this Act) in connection with drug trafficking carried on by him or another are his proceeds of drug trafficking, and

(b) the value of his proceeds of drug trafficking is the aggregate of the values of the payments or other rewards.

(2) The court shall, for the purpose of determining whether the defendant has benefited from drug trafficking and, if he has, of assessing the value of his proceeds of drug trafficking, make the assumptions set out in subsection (4) of this section except that the court shall not make any of the said assumptions if -

(a) the assumption is shown to be incorrect in the case of the defendant, or

(b) it is satisfied that there would be a serious risk of injustice in his case if the assumption were to be made.

(3) Where the court does not apply one or more of the assumptions set out in subsection (4) of this section it shall state its reasons.

(4) The assumptions referred to in subsection (2) of this section are -

(a) that any property appearing to the court -