(4)The exemption granted by Article 33 with respect to any services shall be deemed to except those services from any class of employment which is insurable employment, or in respect of which contributions are required to be paid, under the National Insurance (Industrial Injuries) Acts, 1946 to 1964, the National Insurance Acts, 1946 to 1964, any enactment for the time being in force amending any of those Acts, or any corresponding enactment of the Parliament of Northern Ireland, but not so as to render any person liable to any contribution which he would not be required to pay if those services were not so excepted.
