One objector, representing 3 Hanover Square, said the plans were “poorly devised”.
They said: “The proposed development represents a sizable, dominant expansion of the existing building, effectively enveloping 3 Hanover Square to the west and south.
“Such major change to the town space is, in our view, unwarranted and regretful and would cause a level of harm to the Mayfair conservation area that is not justified.”
However, the proposal was described as “well crafted” and “attractive” by a planning officer, who added that the additional height was not “necessarily harmful”.
Building owners Nautilina Limited said the changes were a “once-in-a-generation opportunity” to build “best-in-class” office space.
The international real estate company plans to move into the 1950s building after it has replaced the seventh floor and built a new eighth floor and rooftop garden.
The approved plans include new retail space on the ground floor for a restaurant.