4.—(1) For the purpose of Article 165(4)(c) (prescribed requirements to be met where an employer is unlikely to continue as a going concern) the prescribed requirements are that the employer is either—
(a)a public body—
(i)in relation to which it is not possible for an insolvency event to occur, and
(ii)which is not the employer in relation to a scheme in respect of which a relevant public authority has either—
(aa)given a guarantee in relation to any part of the scheme, any benefits payable under the scheme or any member of the scheme, or
(bb)made any other arrangements for the purposes of securing that the assets of the scheme are sufficient to meet any part of its liabilities;
(b)a charity which is not a company or other body corporate, or
(c)a trade union within the meaning of Article 3(1) of the Industrial Relations (Northern Ireland) Order 1992(1) in relation to which it is not possible for an insolvency event to occur.