The Barony of Pennicuik, the property of Sir George Clerk, Bart., is held by the following singular tenure: The proprietor is bound to sit upon a large rock, called the Buckstone, and wind three blasts of a horn when the king comes to hunt on the Borough Moor near Edinburgh. On account of this singular custom the family have adopted as their crest a demi-forester proper, winding a horn with the motto, Free for a blast.
Source: wiktionary