I've been told that it was directly across London Road, where Sainsbury's carpark now is. It was accessible by a footpath roughly where the modern one runs alongside Sainsbury's. At the time the carpark was mostly allotments.

There is a similar sign, hard to read now, on the side wall of the locksmith's next to the Dartmouth Arms. It may well have been directing people along London Road.

I must add that I do not remember it, either.