John Nelson, who stepped down as Lloyd’s chairman last year, has called for a second Brexit referendum following a “complete failure” of leadership from the political establishment.

A negotiated settlement along lines proposed by the Conservative Government or an exit with no deal would leave the UK much poorer and less influential than voters were led to believe during the “appallingly conducted” initial referendum campaign, he says.

“We are constantly being told by the Brexiters it will all be fine,” he says in a letter to the Financial Times. “We will keep our sovereignty and… be able to negotiate our own trade deals with ease. This is fanciful.

“Lloyd’s is the most global of all British institutions. Personal experience tells me negotiating overseas rights is a long and painful process.”

Mr Nelson says it is “high time” UK business galvanised the public to understand the realities, while a silent majority of MPs who appear “terrified of putting their head above the parapet” should step forward.

“Of course there needs to be a second referendum once the route we are pursuing becomes clear. That route will bear no resemblance to the picture painted by our politicians at the time of the first one.”