Waddesdon Manor is very French looking but that can be easily explained because it was built by the Rothschild in 1874.
This is free for National Trust members.
It is a very big property get there as early as you can so that you don't miss a thing! There are a few walks and talks that are held daily. I attended the Wine Cellar Talk which is held everyday at 2 pm.
The house is as big as it looks and very French throughout. It even has a table from Marie Antoinette's collection from Versailles.
There is a cafe and restaurant so if you forget to pack a picnic, don't despair. But I highly recommend packing a picnic and relaxing on the grounds.