Complex sentence: However, the late 19th and early 20th centuries were the swan song of the traditional English country house lifestyle, increased taxation and the results of World War I were to result in the demolition of thousands of houses, those that remained had to adapt to survive.
Split into simpler sentences: However, the late 19th and early 20th centuries were the swan song of the traditional English country house lifestyle. Increased taxation and the results of World War I resulted in the demolition of thousands of houses; those that remained had to adapt to survive.