I've actually seen it in the Royal Courts of Justice, too: the Judge allows for contact with the prisoner, but the staff "looking after" the prisoner follow somebody else's rule.
Yesterday, the judge allowed the supporters to visit Maurice in the cells. But when they arrived there, they were told that he had already left which, unfortunately, was not true!...
Go figure: innocent until proven guilty, fair trial or "Cardiff Law": make it up as you go, as long as Maurice is treated as badly as possibly possible - by virtually anybody who has the capacity to abuse their power...