Originally, the estate of Mellerstain was known as Whiteside, the lands of which were given by King James II (1437-60) to Patrick Haliburton, son of Lord Haliburton. They subsequently passed into the hands of the Haitlie family, who may have been responsible for the building of Whiteside Tower, a sixteenth-century fortified house which survives in fragmentary form to the south of Whiteside Plantation.

In 1642, the lands of Mellerstain were granted by King Charles I to an Edinburgh burgess, George Baillie of Jerviswood. They have remained in the hands of his descendants ever since, save for a brief period in the 1680s when they were forfeited following the arrest of Robert Baillie in 1684 for his involvement in the Rye House Plot to assassinate King Charles II. Robert Baillie was subsequently hanged, and his family fled to Europe.

Robert Baillie's son, George, was restored to his lands in 1688 when William, Prince of Orange, was crowned King William III. In 1690, George Baillie married Lady Grisel Hume, daughter of the

Earl of Marchmont, a friend of his father's who had also been exiled during the 1680s. It was during their lifetimes that the initial work on Mellerstain House was undertaken, with William Adam being commissioned to design both the house itself and the surrounding policies.

Work on the building of Mellerstain House ceased with the death of George Baillie in the 1730s. The estate passed, in 1759, via the marriage of George Baillie's second daughter, Rachel, to George, Lord Binning, second son of the Earl of Haddington. He changed his name to Baillie, and it was he who commissioned William Adam's famous son, Robert, to complete the work his father had started nearly 50 years before.