British startup in joint venture with Tokyo Gas, which buys 9.7% stake for $200m

The one-time owner of a London coffee shop now has a paper fortune worth an estimated $155m (£115m) after a deal with a Japanese utility firm valued Octopus Energy, the sustainable energy business he founded little more than five years ago, at $2 billion.

Greg Jackson, a serial entrepreneur, owns a 7.4% stake in Octopus, the UK’s fastest growing energy supplier. Octopus only attained ‘unicorn status’ – a term used to describe young start-up companies worth $1bn – earlier this year. A new investment agreed on Wednesday has doubled that value in the last eight months as it begins its global expansion.