66.—(1) Any finding by a court or industrial tribunal under this Order in respect of any act shall, if it has become final, be treated as conclusive in any proceedings under this Order.

(2) In any proceedings under this Order—

(a)a certificate signed by or on behalf of a Minister of the Crown or a government department and certifying that any condition, requirement or arrangement specified in the certificate was imposed, made or approved by that Minister or that department (as the case may be) and was in operation at a time or throughout a time so specified; or

(b)a certificate signed by or on behalf of the Secretary of State and certifying that an act specified in the certificate was done for the purpose of safeguarding national security or of protecting public safety or public order,

shall be conclusive evidence of the matters certified.

(3) A document purporting to be a certificate such as is mentioned in paragraph (2) shall be received in evidence and, unless the contrary is proved, shall be deemed to be such a certificate.