Whose house is this?

We found this house after driving along a very narrow lane. We needed to get a ticket from a National Trust hut which allowed us to enter at 2:25pm, and get in out of the rain. Inside was a blazing fire in a stove that has been pictured in some books by the person who lived here.
 
Most of the house was kept fairly dark to help preserve the fabrics and pictures. There were a lot of pictures, many by this person's brother and father, and even a hat and some clothes belonging to the person who lived here.

In the kitchen was a basket of vegetables picked from the garden that is also shown in books by the person who lived here.

That person wrote and illustrated this letter to a young friend. It was the start of what this person is most famous for. But they also kept prize winning sheep, and helped set up the early National Trust.