5. For the purpose of calculating the annual rate of any pension payable under Part I or Part II of the Act on the death of an officer, the rate of the superannuation allowance of the deceased shall be deemed to be the rate thereof for which the deceased had become eligible (whether such an allowance at that or any other rate had actually been granted or not) or, as the case may be, for which he would or might have become eligible under the provisions of section four of the Superannuation Act, 1914, of section eight of the Superannuation Act, 1935, and of these Rules, any abatements falling to be made under Regulations made under subsecti on (4) of section sixty-nine of the National Insurance Act, 1946, being left out of account.