1The supply to its members of such services and, in connection with those services, of such goods as are both referable only to its aims and available without payment other than a membership subscription by any of the following non-profit-making organisations—
(a)a trade union or other organisation of persons having as its main object the negotiation on behalf of its members of the terms and conditions of their employment;
(b)a professional association, membership of which is wholly or mainly restricted to individuals who have or are seeking a qualification appropriate to the practice of the profession concerned;
(c)an association, the primary purpose of which is the advancement of a particular branch of knowledge, or the fostering of professional expertise, connected with the past or present professions or employments of its members;
(d)an association, the primary purpose of which is to make representations to the Government on legislation and other public matters which affect the business or professional interests of its members.