Greg Jackson has worn many hats over the course of his career. He co-founded marketing-technology business C360 in the early 2000s and then sold it to the Tangent Group in 2006; after that he went on to work for several companies across various sectors, from healthcare to finance. Then, three years ago, he launched Octopus Energy, a green-energy provider set up to rival the so-called “Big Six” energy companies that dominate the UK market.