Amid all the talk of when and how to end or reverse quantitative easing, one question is almost never discussed: Why have central banks’ massive doses of bond purchases in Europe and the US since 2009 had so little effect on the general price level?

Between 2009 and 2019, the Bank of England injected £425bn — about 22.5% of the UK’s 2012 GDP — into the UK economy. This was aimed at pushing up inflation to the BoE’s mandated medium-term target of 2%, from a low of just 1.1% in 2009. But after 10 years of QE, inflation was below its 2009 level, despite the fact that house and stock-market prices were booming, and GDP growth had not recovered to its pre-crisis trend rate.