What would make a recovery sustainable? If you ask an economist, they’d tell you that what makes any economy grow and prosper is, ultimately, what they call “productivity gains”. That’s the ability to make more with less that allows a people to propser. During the 1990s this was given as the reason why interest rates could remain low and we could have one Hell of a party – a sloppy, hazy bender. We live in the hangover that resulted, but have we really learned how intoxicating this one, simple idea is?