Thanks David and Nigel for your interesting replies.

Although... I'm still curious to know why Moore said there were Cavendishes in the (Kirk Michael) registers from 1611 - I can't find any until the 19th century - Nigel, do you mean he made it up? or was he referring to different versions that are not on film? Was he mistaken? Or what was going on do you think?

By the way, the only William I picked up in Patrick was the one who married Ann Quirk in 1804 and who is down as Corjeage - have I missed one?