In July of 1694 an act of parliament gave William and Mary the right to levy a tax on shipping and beer. In return, they had to dedicate that revenue toward paying back a group of people who would lend them ￡1.2mn. This is the act that chartered what would become the Bank of England. The preamble gives the bank one purpose: the money is to go “towards carrying on the War against France”.

That is no longer the statutory goal of the Bank. But that first ￡1.2mn loan to William and Mary is still treated by economists and policymakers as definitional. Whether to carry on against France or inflation, central banks buy and sell sovereign debt. Any other assets are seen as either political or, worse, not normal: embarrassing panic buys to be shed from the balance sheet as quickly as possible.

In the past two weeks gilts had a swoon, and then a Fed governor said that treasury markets were “functioning well” — two of the most terrifying words in markets. It’s possible that we’re asking sovereign debt to do too much, and right there in that original act there’s an option we keep pretending doesn’t exist: central banks can buy whatever we tell them to.