Tech billionaire Mike Cannon-Brookes has declared himself a “pretty big believer in AGL” who wants to join an overhauled board to decarbonise the electricity supplier after his immediate goal of blocking its proposed demerger is achieved.

Speaking after his dramatic move late Monday to snare an interest of 11.28 per cent in AGL, Mr Cannon-Brookes declared his was “not a short-term commitment” and that he wanted to help steer the company through a decarbonisation process that would be better for shareholders, employees and the country.