Complex sentence: This was achieved but the result was the Marquess and his family returned to make Compton Wynyates their sole country house, thus one of England's most beautiful houses is once again private family house, the purpose for which it was created.
Split into simpler sentences: This was achieved but the result was the Marquess and his family returned to make Compton Wynyates their sole country house. Thus, one of England's most beautiful houses is once again a private family house--the purpose for which it was created.