Where, in accordance with the provisions of sections 249, 264 or 269, a decision or determination is varied or reversed by a deciding officer, an appeals officer or an officer of the health board (as the case may be) so as to disallow or reduce any benefit, assistance, child benefit or family income supplement paid or payable to a person -
(a) any benefit paid in pursuance of the original decision shall be repayable to the Social Insurance Fund to the extent to which it would not have been payable if the decision on the appeal or revision had been given in the first instance and such person and any other person to whom the benefit was paid on behalf of such person, or the personal representative of such person, shall be liable to pay to the said Fund, on demand made in that behalf by an officer of the Minister, the sum so repayable,
(b) any assistance (other than supplementary welfare allowance under Part III), child benefit or family income supplement paid in pursuance of the ori