4. In respect of any lump sum or instalment of a lump sum which became payable in the six months ending with 1st July 1978, but for which the beginning date fell before 2nd January 1978, there may be paid an increase of 3.8 per cent. of the amount of the lump sum or instalment as increased by any increase under section 1 of the 1971 Act or under the existing Orders.