148. Entitlement to pay Class 2 or Class 3 contributions under regulations 146 and 147 shall be subject to the following conditions—
(a)that the payment is made within the period specified in regulation 48(3)(b)(i); and
(b)that the payment is made only to the extent to which it could have been made if the contributor had been present in Great Britain or Northern Ireland (as the case may by) and otherwise entitled to make it.