Impersonating an Impersonation

We can imagine to what lengths Meryl Streep (a fellow alum, if you don't mind my saying!) went to "become" Margaret Thatcher. Here's an account of how Margaret Thatcher herself became Margaret Thatcher: http://www.telegraph.co.uk/news/politics/margaret-thatcher/8999746/How-Maggie-Thatcher-was-remade.html