Plymouth seems to have been the only west country town to have held out for the Parliamentarian cause throughout the English Civil War, and I found it very interesting to research this period of the town's history. Personally, I have always favoured the Royalists (well, I am a romantic novelist and what could be more romantic than the Cavaliers?), but for this story, I had to argue the case for the opposition, as it were, which was fascinating.
In order to study the layout of the town, I visited Plymouth several times, and in particular the so called Merchant's House, which is from the 17th century. I was able to use it as the setting for my heroine's relatives and seeing it firsthand made it much easier to envisage her reactions upon arrival.