"I was out by 200 years and I promise to take a loaded gun into the ante room this very second."

Well if you're going to dismiss the idea of Scottish self determination by quoting facts and dates then one would expect them to be at least close or they are going to be picked up on. 200 years is a long time to add on when the true figure is just over 300. It's not like you were out by a decade or so. At the other end you were even further out by suggesting the Romans set up the border. Especially on the eastern half the border is nowhere near any Roman frontier. The early emerging kingdom of Alba came into being around half a millennium after the Romans had left and the what resembles the present border was more of an 11thC century event at earliest. Of course history affected how the numerous early Dark Age kingdoms came about - but the Scottish nation as such was forged more like three quarters of a millennium after the Romans had left.