Good job Judge - I did intend to rule out the "boats (by implication)" one by my question wording, but your quote about the black rider got round that (I was thinking of the other one).
A bell (or perhaps a bottle of Bell's, since ... brandy ... er ... perhaps not) and the next question is yours, unless you'd rather carry on with this one, and pretend I'd asked for six? See, I'd forgotten about Sarn Ford, and there is another, less obvious means of crossing, which was really the point of the question.
Up to you. If you have a question ready, I'd ask it.