English country houses (fl. 1500-1900) means the country houses of the rich and powerful of England back before the rise of industry, back when land was power, taxes low and labour cheap. Some were just very large houses while others were outright palaces.
In the late 1400s, after the War of the Roses, there was enough peace in the land so the rich could live in houses instead of castles. These large landowners ruled England well into the 1800s. They held most of the top positions in government.
Even those who had made their fortune in trade, in high government office, in sugar in Jamaica and so on, used their wealth to buy a country house and plenty of land to go with it. Because in a country run by large landowners it was the safest and surest form of wealth and power.
The purpose of the land was not to farm it yourself but to receive rent money from those who did.
The purpose of the house was not just to have a nice place to live but to present an image of power: to those who rented land from you and to other rich and powerful people.
Your house not only showed that you had serious money but also that you had taste and intelligence and belonged at the top of society. Even things like the paintings on your wall and the books in your library mattered. A large house also made it easier to have important guests and throw big parties for hundreds of people.
Many had a townhouse in London too. London was the centre of government and business, so most who were rich enough to have a country house had important dealings there. Besides, some found the country deadly dull.
It was unwise to live only in the country or only in the city – since otherwise your interests would suffer in one place or the other. So most lived for months at a time in London and then did the same in the country. When they came to the country they would bring the latest fashions, hangers-on and maybe even a writer or a philosopher.
Before the 1900s working at a country house was a step up in the world for most people: not only was it reasonably secure employment but it meant nice clothes, a good bed and three square meals a day. A country house could employ hundreds.
Country houses were designed for a time of cheap labour and low taxes, when land was the main form of wealth. By the 1920s that world was gone. Country houses became too costly to run and pay taxes on and no longer served much purpose. Many were torn down. Most that remain have become museums, hospitals, schools, hotels and prisons. Only a few still function strictly as family homes.