Complex sentence: The Abbey remained in Henry's estate after he returned to England, and the castle was sold to the Duke and Duchess of Manchester in 1909, they resided there several years, before being forced to sell the house and grounds due to gambling debts.
Split into simpler sentences: The Abbey remained in Henry's estate after he returned to England. The castle was sold to the Duke and Duchess of Manchester in 1909, who resided there for several years before being forced to sell the house and grounds because of gambling debts.