The negotiation of the UK’s new relationship with the European Union will involve a complex process of trade-offs that is increasingly styled as presenting the government with a choice: finance or fish. How will the government balance the needs of bankers and trawlers? Will it sacrifice Canary Wharf for Grimsby Docks?

Whether to favour cod or CDOs may turn out to be one of the government’s trickiest decisions. Yet that is only the start of the complexity.