On the outskirts of Bishopton in Renfrewshire sits a stately former mansion. Its genteel woodland walks and curious masonry have enchanted visitors for decades. Originally Millbank Farm, the estate was purchased by a wealthy stockbroker and art collector, John Augustus Holms. He wanted somewhere special to house his treasures and commissioned his architect friend, Robert Lorimer, to design his estate buildings in the style of a 17th-century tower house. Visitors to the estate will notice a stone archway in front of the former stables dated “1694 DL,” the initials stand…