Can you tell us anything about how the union between Scotland and England affected Northern England’s economic / political importance?

I see what you’re getting at, but that was a more localized phenomenon, where the “border reivers” on either side of the Scottish Marches were really unhappy about not being allowed to raid across the border any more.

More significantly, the North felt ignored and underdeveloped when the South of England began to boom economically as the wool trade took off in the 13th and 14th centuries, and then the cloth trade exploded from the late 14th century through the 16th centuries.

However, this changed rather dramatically beginning with the Industrial Revolution, as industrial manufacturing tended to center in Yorkshire, Lancashire, the Midlands, etc. Thus, for a period in the early 20th century, a suburb of Manchester was supposed to have more millionaires per capita than any other town in the world. But when deindustrialization hit in the later 20th century, the North/South divide reverted to its earlier pattern.