Interestingly the Travellers Times (page 12) linked to above: http://travellerstimes.org.uk/downloads%5CTT29_05042009215333.pdf
gives advice on how to deal with such signs if seen. This includes reporting them to the local police, the CRE, and the local licensing authority. (and, if necessary opposing the re-issue of a license)
If more people took this sort of action then evidence of these signs would start showing up in official documentation.(and possibly the newspapers)

Jim: you said "where I found these signs (last year being the last ones I saw), " If it was that recently, did you report them?