"1(2) In preparing [the final decision or judgment] the Tribunal shall have regard to the need for excluding so far as practicable- (a) information the disclosure of which would in its opinion be contrary to the public interest; (b) commercial information the disclosure of which would or might, in its opinion, significantly harm the legitimate business interests of the undertaking to which it relates; (c) information relating to the private affairs of an individual the disclosure of which would, or might, in its opinion, significantly harm his interests. (3) But the Tribunal shall also have regard to the extent to which any disclosure mentioned in sub-paragraph (2) is necessary for the purpose of explaining the reasons for the decision."