Eighteen months ago, Venezuela seemed to be on the brink of political upheaval. The leader of the National Assembly declared himself president, and 50 countries offered him official recognition. But the ruling party has not been toppled. Nicolás Maduro is still in the presidential palace, overseeing a country deep in economic and healthcare crisis. HARDtalk’s Stephen Sackur speaks to Vanessa Neumann, London envoy of the would-be president Juan Guaidó. Did the Venezuelan opposition blow their chance?