Where the final balance of the estate of the deceased does not exceed twelve thousand pounds, there shall, in respect of the succession acquired by the husband of the deceased in her dutiable estate, be deducted from the estate duty calculated in accordance with the scale of rates set out in the First Schedule to this Act an amount bearing the same proportion to that duty as the value of that succession or the amount of one thousand pounds (whichever is the less) bears to the amount of the final balance of the estate:

“Provided that, subject to the provisions of subsection four of this section, the amount of the deduction shall where necessary be reduced so as not to exceed the maximum allowance.”

Where it is discovered after the expiration of ten years from the date of the death of a person (whether the death occurred before or after the commencement of this Act) that the estate duty payable in his estate has not been fully assessed and paid because of material facts not originally disclosed, and the Commissioner is satisfied that the nondisclosure of those facts was not due to the wilful act or negligence of the administrator or other person liable to pay the duty, the Commissioner may, on special grounds, remit the duty so unpaid together with the interest thereon.

For the purposes of subsection four of this section—