Her pounds 3.5m acquisition of the former Highland family seat of the Frasers of Lovat in August marked the culmination of a remarkable rags-to-riches story.
Ann Gloag was born 53 years ago this month, the daughter of a bus driver. She started her working life in a local hospital, becoming a theatre sister. In her early twenties she married Robin Gloag and had two children. In 1980 Ann and her brother Brian used their father's pounds 25,000 redundancy money to found Stagecoach. Robin became a director.
Ann had left nursing and begun dabbling in business - selling antiques and hiring out caravans and minibuses. But the ventures had not been great successes. Stagecoach began running a single route with second-hand buses in Dundee. It expanded aggressively in the mid-1980s when Britain's bus industry was deregulated.
By this time Ann and Brian had voted Robin off the board after "differences of opinion". His pay-off amounted to a bus and a few thousand pounds. An acrimonious divorce followed. He set up a rival local bus company, Highwayman. Ann's response revealed the aggressive competitiveness that has become her trademark. Stagecoach's fares were cut and eventually Robin withdrew his service.
Dispirited rivals condemn Mrs Gloag as a ruthless operator. But others say she was simply the first to consolidate Britain's fragmented bus industry and enjoy the economies of scale.
She refuses requests for interviews and declined to take part in a BBC film about Stagecoach. When she heard it would criticise her business practices, she spent pounds 70,000 on newspaper ads castigating the BBC and its methods, headed: "We'll take the high road, while they take the low road." It would make a fitting motto above the imposing gates of Beaufort.