the provision of Case F of these Regulations shall not apply;

the weekly rate of any Class 2 contributions payable by a volunteer development worker for any contribution week while he is ordinarily employed as a volunteer development worker shall, notwithstanding the provisions of section F111(2) of the Act (Class 2 contributions) be 5 per cent. of the lower earnings limit for the year in which falls the week in respect of which the contribution is paid;

for the purpose of determining the extent of an earner’s liability for contributions under regulation 21 the amount prescribed in that regulation shall be reduced by the amount of any contributions paid in respect of the year in question by virtue of regulation 151; and

regulation 89 shall not apply.