The Yes California website states: “We advocate for peaceful secession from the United States by use of an independence referendum to establish a mandate, followed by a nationwide campaign to advocate in support of a constitutional exit from the Union.”

Generally characterised as a fringe campaign, it nevertheless has some high profile backers, including Silicon Valley luminaries such as Shervin Pishevar, co-founder of Hyperloop, who yesterday announced on Twitter that he planned to fund a “legitimate campaign for California to become its own nation”.

Speaking to CNBC, he described his backing for Calexit as “the most patriotic thing I can do,” adding: “We can re-enter the union after California becomes a nation. As the sixth largest economy in the world, the economic engine of the nation and provider of a large percentage of the federal budget, California carries a lot of weight.”