Leadership matters. So does an ability to solve complex problems successfully. But, when push comes to shove, the politicians who survive and prosper are those fortunate enough to lead countries during an economic upswing.

In 1979, when Margaret Thatcher became Britain's first female prime minister, amid global stagflation, the omens did not look good. The going got tougher when Federal Reserve chairman Paul Volcker - and the Thatcher administration itself - applied tight monetary conditions to squeeze inflation out of the system.