Thatcher died following a stroke Monday at the age of 87. She had withdrawn from public life years ago due to a battle with dementia.
In addition to an Oscar, Streep also won a Golden Globe Award in 2012 for her portrayal of the conservative, controversial leader as an elderly, confused woman, now retired from office and looking back at some of the biggest milestones of her life.
"All of us understood -- through a process of a year before we started shooting -- what we were wanting from this piece," Streep told UPI at a news conference in New York before the film's theatrical release. "That it was going to be, not a docudrama, not a chronicling of Margaret Thatcher's political life. That it would be a very particular look back through her own eyes at selected memories, not in chronological order, in a jumble of memory, regret, glory days. That it would all be part of a reckoning at the end."
Although Streep said she never had the opportunity to meet the former prime minister, she recalled going with her daughter to hear her speak at Northwestern University more than a decade ago.
"That made an indelible impression on me," the actress told reporters.
Asked if she felt a responsibility to Thatcher at the time since she was still alive and might see her performance, Streep replied: "We have come under criticism for portraying a person who is frail and in delicate health.
"Some people have said it's shameful to portray this part of a life, but the corollary thought to that is, if you think that disability and dementia is shameful, if you think the ebbing end of life is something that should be shut away, ... if you think that people need to be defended from those images, then, yes. If you think it's a shameful thing then, yes," she continued.
"I don't think it's a shameful thing. I have had experience with people with dementia. I understand it. I think it's natural. We are naturally interested in our leaders. And we tell stories about ourselves through the stories of important people. Going back to '[King] Lear' and deciding questions of existence through 'Hamlet.' We're not talking about Hamlet's politics or whether Lear was a good leader. We're talking about the loss of power because it's interesting."