John C. Van Horne, Editor, in Collaboration with the Papers of Thomas Jefferson at Princeton University and the Center for Digital Editing at the University of Virginia.
Newly Discovered Watercolor Featuring Washington’s War Tent Anchors Limited-Run Exhibit “Among His Troops,” Jan. 13 – Feb.
If you check The African Americans: Many Rivers to Cross, you will find the story of Harry Washington. I checked with the Washington Papers staff before writing that and the problem with "Harry Washington" is that several slaves Washington owned bore the name Harry, something that Phybus was unaware of. Which of the several you are interested in may be impossible to determine. If you have some additional evidence I suggest you contact the Washington Papers for additional information.
I do not know about HW's relationships at Mt Vernon, but the 1784 Birchtown Muster lists him as being married to "Jenny Washington."
Pybus suggests that "This person could be Jenny Coddamus who is twenty four and travels on board the Clinton with two small children. Harry and Jenny and their children relocated to the British colony of Sierra Leone in 1791."
See here: http://www.blackloyalist.info/person/display/1485