(b)for the purpose of the application of this sub-section to any case where before the commencement of the winding up or insolvency a proportion of such profits as aforesaid of a branch only of the life insurance business in question has been allocated to policy-holders, the value of the assets and liabilities of the insurer in respect of that branch shall be separately ascertained in like manner as the value of his assets and liabilities in respect of the life insurance business was ascertained, and the surplus so found, if any, of assets over liabilities shall, for the purpose of determining the amount to be added to the liabilities of the insurer in respect of the life insurance business be deemed to be the prima facie surplus.