Industrial action shall be regarded as having the support of a ballot only if—
it is called by a person specified or of a description specified in the voting paper for the ballot in accordance with section 229(3), and
there was no call by the trade union to take part or continue to take part in industrial action to which the ballot relates, or any authorisation or endorsement by the union of any such industrial action, before the date of the ballot.
For the purposes of this section a call shall be taken to have been made by a trade union if it was authorised or endorsed by the union; and the provisions of section 20(2) to (4) apply for the purpose of determining whether a call, or industrial action, is to be taken to have been so authorised or endorsed.