Suzanne Buchta recalls meeting with a Swedish investor interested in green bonds, who asked her if she had heard of guidelines on how bonds issued to finance environmentally friendly work should be structured and sold. Yes, Bank of America Merrill Lynch’s London-based managing director for green bonds replied – she co-wrote them.

Those principles, written with Michael Eckhart, Citigroup's head of environmental finance, and launched in early 2014, today have 56 underwriters signed up as well as 30 investors and 23 issuers, and are now overseen by the International Capital Market Association.