"Margaret Thatcher was an incredibly polarizing figure, but everyone should be able to agree that she was absolutely spot on about why the Euro would be such a disaster.
As Peter Oborne reported in the Telegraph In 2010, Thatcher's two autobiographies, "The Downing Street Years" (1993) and "The Path To Power" (1995) discussed the tactics she would use to argue against the EMU (Economic and Monetary Union), which she wanted no part of.
Basically, she outlined the problems with the euro perfectly, that Germany would chafe at the inevitable need for greater inflation, and that the poorer countries would inevitably be uncompetitive and need bailouts that would not easily be forthcoming.
This paragraph is from "The Path To Power," where she discusses conversations with John Major (her successor) about negotiating with the rest of Europe. She just totally nails the inflation and competitiveness angles."