39.—(1) For the purposes of all the stages of collective bargaining between an employer and representatives of an independent trade union about matters and in relation to descriptions of workers in respect of which the trade union is recognised by that employer, it shall be the duty of the employer, subject to Article 40, to disclose to those representatives on request all such information relating to his undertaking [F1(including information relating to use of agency workers in that undertaking)] as is in his possession, or that of any associated employer, and is both—

(a)information without which the trade union representatives would be to a material extent impeded in carrying on with him such collective bargaining; and

(b)information which it would be in accordance with good industrial relations practice that he should disclose to them for the purposes of collective bargaining.

(2) In this Part—

• “recognised”, in relation to a trade union, means recognised by an employer to any extent for the purpose of collective bargaining;

• “representative”, in relation to a trade union, means an official or other person authorised by the trade union to carry on such collective bargaining as is referred to in paragraph (1).

(3) Where a request for information is made by trade union representatives under this Article, the request shall, if the employer so requests, be in writing or be confirmed in writing.

(4) In determining, for the purposes of paragraph (1)(b), what would be in accordance with good industrial relations practice, regard shall be had to the relevant provisions of any Code of Practice issued by the Agency under Article 90, but not so as to exclude any other evidence of what that practice is.

(5) Where an employer is required by virtue of this Article to disclose any information to trade union representatives, the disclosure of it shall, if they so request, be in writing or be confirmed in writing.