Nuns and Irish priests in 18th century England

For God's sake...don't the people who make these films have even the most basical historical knowledge...why on earth where there nuns, 'Oirish' priests in confessional boxes, statues of the BVM in churches etc in this film?

There were no nuns, priests, or anything like that in England in the 18th century - it was illegal to practice Catholicism between the 16th and 19th centuries in England.

At this point early on in the film I gave up, because if they can't even get basic historical details like that correct, what's the point?