Jim:
"I keep repeating that the signs are not common throughout Britain because that is my whole case."
My point exactly - no evidence to contradict the evidence produced

Has it ever been explained to you that it is very difficult (if not impossible) to prove a negative.

If you can provide examples of many places where these signs may currently be found then you would be justified in stating that they are 'common' in the UK.
Until such time as you can 'prove' your accusation, we can rely on the UK's presumption of innocence.