We were writing historical conjecture, and Mr. Brown was writing a novel.

Mr. Brown was writing a novel, and these kinds of finer details of history presumably weren't at the forefront of his mind.

Total coincidence, at least from our side.

I think my language was infelicitous and I think I have to agree with you on that.

Unfortunately, in this case, there are no facts.

My conclusion would be I've got no idea where Mr. Brown got his information from. He didn't get it from me.