Dorothy Angest was granted a house of multiple occupancy (HMO) licence to turn a listed residential house in one of the oldest areas of Aberdeen into a property for students.
But Ms Angest, wife of Henry Angest - the Swiss banker and chief executive of the Arbuthnot Banking Group - has angered neighbours with the move.
Local residents claim the granting of the area's first HMO licence will spoil one of the "most historically significant streets" in the city.
Ms Angest went before the city council's licensing committee earlier this week in a bid to turn No 2 The Chanonry - a category B-listed building - into studentflats.
Her son is understood to be studying with friends at the University of Aberdeen.
Ms Angest was granted the HMO licence, despite eight objections. Residents argued at the meeting that the area was not only locally important but also of national significance.
Gordon Mutch, vice chair of Old Aberdeen Community Council, said: "Old Aberdeen is approaching a tipping point where property becomes less attractive due to the proximity of HMOs."