Hi James,
I appreciate your explanation, however, the use of this wording in the title can be viewed as a contentious one. There may be buyers out there that just don't know or aren't aware that the vase wasn't produced or even designed by Michael Harris. Whilst there may be an argument for including Michael Harris in the title for the purpose of aiding item searches, at the same time it may be worth explicitly saying in the items description that the vase is not a Michael Harris design.
Greg