“Controversial” term is used by the MSM to imply that person had employed questionable methods or had views out of mainstream (as they understand it). Therefore, Obama, for example, can never be called controversial.
I would have taken ‘non controversial’ to mean someone who was moderate or middle-of-the-road. Someone who tried to compromise rather than defeat their rivals/enemies. Previous Tory Leaders had tried to reach a consensus (at least within their own party) Thatcher did not, she was a polariser. The term ‘controversial’ fits her any way you put it, and I admire most of what she did....