She is a great rebuttal to any feminist types who still use the same old excuses why it is harder for a woman to do anything in the fields of politics, or the workplace, or wherever. Whenever left wing and liberal political advocates talk about implementing and forcing quotas for female politicians (the phrase we have is "all female shortlist" for party candidates), it is great to remind them that a determined, strong woman was able to become leader of her party and then the UK, in the 1970s. She didn't need a quota system, and she had to fight to rise to the top like any man would have to do.
You don't have to agree with her politics to recognise that she demonstrated the necessary characteristics, and her gender didn't stop her achievements.