"I know from my own experience that it is not."
How can you possibly know that

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This thread is getting really silly. You have provided evidence that such signs existed so that is fair enough however the main argument seems to be against the assertion that they were 'common' in Britain. Posts from people who have lived in Britain for a long time seem to say that they had never seen such a sign. If they were 'common' then most people would have seen one at some point! It's pretty obvious that they are either a rare occurance - or that we are all lying! I know I'm not and I have no reason to believe that all the other posters are lying either. This whole thread seems to be down to an exaggeration! They may exist, or perhaps have existed, but they don't seem to have been at all common!