I should have clarified that more in the Q&A and i shall amend it. Brian is correct.
The problem lies in the fact that replicas were grandfathered, but there is no strong basis to prohibit ownership. A prohibited weapon that has been grandfathered requires a prohib PAL - you can't have one without the other. But without any sort of licensing for replicas, you can't grandfather them and make their possession illegal at the same time.
And as Brian pointed out, trying to charge you on the basis that you may or may not have bought a toy gun after 1998 is not exactly priority business for the courts.