My March release, Flavour of Our Deeds, is partially set in Northumbria.
I wanted my hero and heroine far away from their natural allies, faced on all sides by enemies and uncertain who to trust. Learning a bit about Northumbria introduced all sorts of new plot elements.
For example, did you know that the Coquetdale area of Northumbria was a whisky distilling area (whisky is the Irish, Scots and, as it happens, English borderlands spelling of what the US call whiskey). Coquetdale, in what as now the Northumberland National Park, was full of illegal stills that exported their product not just south into the rest of Northumbria, west into Cumbria, and further afield in the United Kingdom, but also by ship to the Lowlands. The distillers were supported and protected by the locals.
The smugglers carried whisky and wool overseas and brought back genever (Dutch gin) and luxury goods from the continent. They had havens in fishing villages like Boulmer, on which I have based my own fictional village, close to the shore. I’ve removed a few aristocratic families–in my story, the Earls of Grey and their home, Howick Hall, is not mentioned, and nor is Alnwick, Alnwick Castle, or the Duke of Northumberland whose residence the castle was. The sea caves are real, and were used by the smugglers. The excise men did, indeed, have a base at Berwick Upon Tweed, and another at Newcastle, and were too few in number to make much of a dent in the trade.
I would have loved to set the story closer to the Roman wall, but I needed limestone for a good caving system that could be improved by enthusiastic tunnelers. A vast maze of caves was once discovered under Alnwick Moor, and has now been lost again, but caving experts believe there may be many more tunnels and caves than those shallow hollows known to our modern cavers. I’ve invented some, putting it in limestone country to make it plausible.
I’d also have loved to include the Holy Island of Lindisfarne. Maybe another time.