The problems with the Big Four audit firms didn’t start with Carillion, they actually began one Friday back in January 1990. You could say that was the last time an auditor tried to give a straight answer to a straight question.

With a client and its prospective buyer in the room, an auditor by the name of Martyn Bishop was asked whether his firm’s audit of the company’s accounts gave a true and accurate state of affairs. Put on the spot, Bishop said he stood by the accounts, and so set in motion a disastrous chain of events that brings us up to cases like the Carillion collapse today.