Hi Ian!An interesting question and one that sent me to the encyclopedia.
"Real estate means an interest in land other than a chattel interest. Real estate is sometimes called real property. A house is real estate, but the rugs and furniture in it are chattels, or personal property.
"The term real property came into use from the fact that, in the case of contest over the title, the rightful owner received the real (actual) property."
Now tell me why a simple freehold house built by Wimpy is an "estate house?" Not the best term that could be used when people ordinarily associate the term "estate" with something somewhat grander!
All the best,
Dan