Paragraph 6
Where—
the person is in pensionable employment at the end of the contribution period,
the principal election has not ceased to have effect under paragraph 7, and
at any time during the contribution period the person has been in part-time pensionable employment
he may, at any time before he becomes entitled to payment of retirement benefits, by giving written notice to the Secretary of State elect to make an additional lump sum contribution determined in accordance with sub-paragraph (2) (so that paragraph 2 of Schedule 7 shall apply).
The additional lump sum contribution referred to in this paragraph is such sum as would be payable under Part II of this Schedule in order to count as reckonable service a period equivalent to the difference between the length of reckonable service arising from the contribution period and the length of such service if the person had been in full-time employment throughout the contribution period.