4 Increase in certain lump sums
1 This article applies to any lump sum or instalment of a lump sum which became payable on or after 11th April 2005 but before 10th April 2006.
2 The pension authority may increase a lump sum or instalment of a lump sum to which this article applies by 2.7 per cent of the amount of the lump sum or instalment (as increased by the amount of any increase under section 1 of the Act of 1971 or under the existing Orders) multiplied by—
AB
where

a
A is the number of complete months in the period between the beginning date for the lump sum or, if later, 11th April 2005 and the date on which it became payable; and

b
B is 12.