Basically the UK is a complicated entity, thus the high number of books from the British Isles that my journey is ending on - and that's before we get into The Republic of Ireland, along with the Isle of Man, and the Bailiwicks of Jersey and Guernsey (the latter three being Crown Dependencies but not part of the UK itself).
Rather than trying to untangle all of this historical confusion, I have added a link to a video that ably explains all in 5 minutes much better than I could! (Although it omits the Principality of Sealand which proclaimed independence from the UK back in the 60s and is still going strong, of which more later...)
Sitting comfortably? Then let's begin...