I'd recommend reading "The Harington Family" by Ian Grimble, if you can find a copy second-hand. It's not cheap these days, but well worth it if you want to know more about the noble/gentry Harrington family from Osulf down, including the Lords of Aldingham, the knights of Hornby Castle, the Exton branch, Sir William who bore the Royal Standard at Agincourt in 1415 etc.
Looks like more research is in order.
I wonder if our library would have that book and I'll check on Amazon. Thank you!