Hey everybody! I'm new to the forum, but I'm a pretty experienced modder with Medieval II.
I am directly descended from the Pomeroy family, whose castle still stands in South Devon, England. If my ancestor Sir Thomas Pomeroy had not sold the castle to Edward Seymour, the Duke of Somerset, in 1547, my cousin John would be the owner of it today!
Here's the Pomeroy family coat of arms:
So, the moral of the story is: don't sell your castle to your immediate lord for a small plot of land south of York.