“Military Headquarters of General Gage”?

Last month Boston 1775 reader John C. Beasley sent me a query about this picture of a house from Old Boston Days and Ways, written by Mary Caroline Crawford and published in 1909. It appears on page 86.

The caption identifies that building as Gen. Thomas Gage’s “military headquarters,” which raises two questions:

• What’s the basis for that statement? Old Boston Days and Ways doesn’t mention this building anywhere else.
• How does this caption square with Crawford’s statement on another page that Gage used the Province House as his Boston headquarters?
  

The Province House (often called simply “Province House”) was a large brick house on a spacious lot across from Old South Meeting-house, a couple of blocks from the center of town. Massachusetts maintained that house as the official residence of royal governors. Most histories agree Gage lived and worked there. Crawford’s book includes a picture of the Province House, so she clearly knew this was a different building. But what building was it?

TOMORROW: House hunting in colonial Boston.