Well this Yorkshire/Lancashire thing has been going on for centuries.

I visited Bosworth Field yesterday (Leicestershire) on my way back from Manchester, Lancs, via Chester, Cheshire and was informed that even those who lived in Yorkshire probably fought on the Lancastrian side. Gentleman behind the counter said that it was more a North/South divide, with the Lancastrian stronghold being the more northerly counties. There's an interesting map that shows which lords came from where and what colour they liked their roses. It did indeed show that most of the Lancastrian supporters came from the North and the South West. So even if you lived in Yorkshire, it's highly likely you (well, your local lord) were a Lancastrian supporter. I was pleased to see that the only lord I've ever found in my family history wasn't at the battle - he obviously preferred his roses yellow (Peace).

LTS
Loyaltie me lie