I am rather frustrated as well that no lawyer in the UK has tried to do the same thing Matt and I are doing here: that is, provide information and a low cost way to address Getty's claims. Here is the language of the relevant section of teh UK Copyright Act:
97 Provisions as to damages in infringement action.
(1)Where in an action for infringement of copyright it is shown that at the time of the infringement the defendant did not know, and had no reason to believe, that copyright subsisted in the work to which the action relates, the plaintiff is not entitled to damages against him, but without prejudice to any other remedy.
This should be all anyone needs to raise to put an end to Getty's claims.