regshoe

"I don't know how much Broster's original target audience in 1925 could be assumed to know about the '45"

My impression is that, through the first half of the twentieth century, it's not so much that people necessarily remembered all the details of the actual history, even if they learned them at school, so much as that they became entranced in childhood with the myth of the Jacobite Rebellion.

Tales of Bonnie Prince Charlie (like knights in shining armour, Mary Queen of Scots, and gallant Royalists vs wicked Roundheads) were mainstays in romantical children's historical fiction, at least in Britain. This means that, to contemporary readers, Culloden would indeed be a familiar battle, at least by name, along with the exciting story of the Prince's escape afterwards.