David Blood proudly holds up on a Webex screen a framed Economist article written in 2004 when the former Goldman Sachs banker, together with Al Gore, a former American vice-president, set up a new investment firm, Generation Investment Management. It includes the inevitable quip about men named Blood and Gore launching a sustainable-investing business. But he is keener to point out the title, “Does it add value?” He says: “This may be your question today.”