Is it any wonder that furriners don't understand all this, when we who live here are so often confused? :-) When we were in Mudeford, in Dorset, there were lots of small boat operators offering day trips to the Isle of Wight. From the fact that they all prominently stated that no passport was required, I can only imagine that people frequently assumed otherwise. I doubt there are hordes of foreign tourists in Mudeford, so it's probably mostly British people making this mistake.

Although the Isles of Man and Wight are classed along with Calais in Kingmaker, as isolated places that can't even be reached by news of peasant revolts. :-)