§ Amendment made: No. 18, in page 16, line 27, at end insert:
'where, having regard to the purpose which that item or part is intended to achieve, the arbiter is satisfied that the last-mentioned method or material would involve undue difficulty or expense, that the first-mentioned method or material would be substantially as effective for that purpose, and that in all the circumstances the substitution is justified'.—[Mr. Strang.]