Early Prediction Markets

I’ve been rewatching Showtime’s The Tudors, which led me to do some googling to check how much of the portrayal of George Boleyn is based on fact. In the process I came across this gem from Wikipedia:

Everyone who witnessed George's trial, including the Imperial Ambassador Eustace Chapuys, confirmed that he put up a magnificent defence and many thought he would be acquitted. Chapuys confirmed that those watching were betting 10 to 1 that he would be acquitted and the court chronicler Charles Wriothesley said that his evidence was a marvel to hear….

…Yet whatever Jane Rochford may or may not have said, it seems that the majority of the courtiers believed in his innocence, as can be seen from the wagers they were making in favour of acquittal.

I love it: Historical accounts of this period are rife with speculation, since the statements made by people of the time have to be filtered through the lens of the political incentives motivating speech; the sincerity of a betting market, on the other hand provides hard evidence. Of course, we still need to trust that Chapuys was telling the truth when he reported on the betting markets…