The question presupposed that there is such a thing as "History," presumably meaning a consensus of opinion among historians, ie academics leading very comfortable lives compared to most people. Somebody once said "A professor is a policeman of the intellect."
In fact there are as many versions of history as there are factions/special interest groups in a society. Ruling elites attempt to control history, often by the use of ritual and symbolism (acts of real magick) of which Thatcher's state funeral was a good example. Sometimes these rituals are derailed as in Diana's funeral- but the Establishement moves swiftly to repair any damage done. By controlling the past they control the present and the future.
But meanwhile the downtrodden and the dispossesed pass on their own histories, in whispers maybe, or in disguised forms. The internet has made a huge difference, but not as much as could have been- Wikipedia is a powerful tool for the elites to regain control of history, because most people are so lazy they'll go direct to wikipedia rather than trawling through dozens of different sites. Still, much of the truth is out there for those who can be bothered looking. I say "much of" because there are still rumours about recent history that don't seem to appear online.
Anyway, insofar as a consensus is achievable, I think that even her fans would surely agree that she was the most divisive figure in 20th century UK politics. Until Tony Blair she was also the most hated. I don't mean by everyone, of course. But Thatcher's opponents hated her with a real, gut-level hatred and rage that no other previous politician had evoked. And we still do.