http://www.themodernantiquarian.com/forum/?thread=18136&message=199789
Sorry, I probably should've posted it to this thread!
Perhaps older maps of the area are the way ahead... Although I'm sure I could find Worm's Rock, given a few hours walking along the river at Wearside.
Isn't Lambton Castle the ancestral home of the Lambton family? If this is so, then I think its safe to say that this is what's meant by Lambton Hall.