45 It follows that if the substituted para (c) of the defini¬ tion of "artistic work" had been included in the definition of that expression in the 19 78 Act, there could have been no doubt that it would have operated retroactively: And the mere fact that it was substituted by amendment in 1983 cannot have a different result. Butt's counsel did not quarrel with submission (b). Clearly any copying by Schultz before 17 October 1983 was not an infringement because prior to that date no copyright existed in respect of works of craftmanship of a technical nature, and there is nothing in the 1983 amendment which makes conduct unlawful which was lawful when it was committed. In.......