It was there in black and white, one of the most important promises ever made by the political class to the Great British public: a sacred, unbreakable contract between government and voters.

“The referendum … is your chance to decide if we should remain in or leave the European Union”, the government told us solemnly in its 23 page, taxpayer-financed propaganda brochure, making its final case. “This is your decision. The government will implement what you decide.”

The message was crystal clear this was a historic constitutional moment.