Eleven kilometers (6 3/4 miles) northwest of Kelso stands Mellerstain, the seat of the earls of Haddington. This is one of the most famous mansions designed by Robert Adam and one of Scotland's greatest Georgian residences. William Adam built two wings on the house in 1725; the main building was designed by his more famous son, Robert, some 40 years later.

Mellerstain is associated with Lady Grisell Baillie (born Grisell Hume). When she was 13 years old, in 1689, her father was suspected of plotting to assassinate Charles II. The young Giselle showed great courage by hiding her father in the village church's crypt, bringing him food and supplies in the dead of night, and facing down the English. She eventually fled to Holland but returned in triumph with William of Orange (later William I of England) and subsequently married into the Baillie family, scions of Mellerstain. You can see the interior, with its impressive library, paintings, and antique furniture. The garden terrace offers a panoramic view south to the lake, with the Cheviot Hills in the distance. Afternoon tea is served, and souvenir gifts are on sale.