And as has been pointed out elsewhere, there were noble families during that time who were openly Catholic, many of them with private chapels and chaplains. Heck, there was at least one Queen during that period that was Catholic. Also, the "12 days" doesn't deal with any of the major points of difference between Catholiscism and Church of England.

I also believe it HAS been used to teach catachism, but "secret teaching"....nope....