She was a woman, and her gender is quite important here as she remains to be the only ever female, British Prime Minister.
I can’t say I know much about her and what I do know mostly comes through her Wikipedia page which I read before reading this article.
As I hear she was born into a family where her father owned two grocery shops, and lived above the larger of the two.
Before she became Prime Minister she had a series of roles within British Parliament: first as Education Sectary and the leader of the opposition. I’m really not very good at obituaries.
She became Prime Minister in 1979 and resigned in 1990.
Margaret Thatcher lived the remaining few years of her life in bad health before dying of a stroke in 2013.
Here’s a picture of current Prime Minister; David Cameron, paying tribute to Margaret Thatcher.