User blog comment:The Spie/Head-Canon Volume I: England/@comment-1616397-20100120064622

Well, it won't tell you about Ireland, but for a great history lesson on the British Isles, I highly recommend Mike Ashley's "The Mammoth Book Of British Kings and Queens". However, get the trade paperback version (which you can find used on Amazon), not the smaller paperback version. The latter begins at 1066. The trade paperback goes back to the Roman era, and provides a chronological list by territory of all known and rumored British rulers. It brilliantly shows the evolution of Britain into a United Kingdom, and gives you a great introduction to the Brit-tans' bosses.