BALCASKIE is the story of Scotland's unsung architectural genius, Sir William Bruce (1630-1710), who planted the baroque style in Scotland's dramatic landscape, and with his masterpieces - Kinross House and the Royal Palace of Holyroodhouse - established a vigorous strain of Continental classicism equal to any in northern Europe.

This achievement was nurtured at Balcaskie, an unassuming laird's house and estate in Fife that he bought in 1665 as his own seat. His remodelling of the existing house and designs for the landscape were the testing ground for the evolution of his taste and practices as an architect.

The property was bought in 1698 by Sir Thomas Anstruther, scion of an ancient Fife family. Today his descendant Toby Anstruther lives in Balcaskie and is immensely proud of being the guardian of Bruce's remarkable house. Architecture rather than ancestry has always been his primary interest, instilled in him by his architect mother, whose idea of a family holiday was a cultural tour abroad with Banister Fletcher's bible of world architecture to hand; in England it was Nikolaus Pevsner's county guides. In a romantic twist, Toby Anstruther is married to Kate Pevsner, granddaughter of the architectural historian.

"We are very lucky to have such a beautiful house," he says. "It is easy to take history, particularly one's own, for granted, but I never cease to wonder at the quality of what Bruce designed and built, and it is a real privilege to live at Balcaskie. Bruce certainly deserves his place among the greats of Scottish architecture."

Bruce was one of the very first architects in Britain to tie the design of his house to the surrounding untamed landscape; and as this was Scotland, his canvas was immense. He centred Balcaskie on a view of the Bass

Rock, a striking volcanic island that emerges some miles out in the Firth of Forth. To lead the eye, he constructed a formal garden of massive stone terraces, French in their ambition and scale, that fall away from the house to a distant avenue of trees, which in turn directs the gaze to the sea and the shimmering eye-catcher beyond. This

brilliant effect anticipated by a good 40 years or more the cult of the picturesque, which inspired architects to make the best of a good view. His entrance front was aligned with Kellie Castle, a tower house of great antiquity, a mile distant.

Balcaskie was Bruce's stepping stone to architectural greatness. His growing reputation with the Lords Commissioners led to his appointment as Surveyor General of Royal Works in Scotland, with the Royal Grant specifically mentioning his "skill in architecture".

Previous holders of this post had been responsible for the finances of projects, leaving highly skilled royal master masons in charge of design and building. Bruce's promotion singles him out as the first actual architect in Scotland.

Bruce did not allow his new post to distract him from his tax-collecting duties. He was a financial as well an architectural wizard and led the syndicate that won the lucrative contract to "farm" the taxes for the rebuilding of Holyroodhouse, thus receiving double payment for his work. One grandee dismissed him as a "teuch [tough] lawyer"; others admired his dynamism: "Your lordship and I," wrote Viscount Tarbet to the Duke of Gordon, "have known him a vigorous little man as could be."

Bruce's reconstruction of the Palace of Holyroodhouse is one of Britain's earliest and finest essays in Continental classicism. But even at the palace there is a royal nod to Balcaskie. Twin Renaissance towers project at either end of the correct classical screen of the entrance front. One tower is genuinely old, the other newly built by Bruce to match, just as he had balanced the composition of Balcaskie with an old and a new wing. In return, a touch of royal splendour was bestowed on Balcaskie-a suite of sensational plaster ceilings created by the English craftsmen responsible for the decorative scheme at Holyroodhouse.

"No doubt on a Friday afternoon," suggests Anstruther, "the team would be shipped over from the port of Leith with Bruce saying, 'If you want to get paid, do some work here.'"

Bruce left Balcaskie in 1685 to start afresh with his next house, Kinross. Since then, Balcaskie has settled down to quiet centuries of ownership by the soldiers, lawyers, public servants, and courtiers who have headed up the Anstruther family. Toby Anstruther inherited from his cousin Sir Ralph, who was the legendary Comptroller of the Queen Mother's household. The family have treated the house with habitual good manners, their only major faux pas being the building over of the entrance court. It is their accumulation of portraits, furniture, and country house clutter that gives the house its patina of history, which has settled gently over William Bruce's revolutionary structure- the first indication of the genius that was to earn him the posthumous title of "chief introducer of architecture to this country".

This is an edited extract from Scottish Country House by James Knox, published by Thames & Hudson, £18.95