A couple of weeks ago, I mentioned that I had been sent a copy of The Great British Adventure Map. It’s now on my wall in such a position where, every morning, I spend a few minutes staring at it as I shave. Such is the level of detail that it’s the kind of map that will see me shave my chin many hundreds of times before I have exhausted its facts and figures. In recent days, however, my eyes have been drawn north. North west to be precise to a corner of the map that has had me examining the Outer Hebrides…