Friends of the Earth has welcomed a report from a leading investment bank that petrol giant ExxonMobil's bad environmental record is a risk to its business.
The environmental pressure group mounted a visual protest last week to coincide with Deutsche Bank's warning.
It is protesting against the oil firm's sponsorship of the National Gallery's Madame de Pompadour: Images of a Mistress exhibition.
An activist dressed up as Madame de Pompadour to hammer home the group's message to visitors of the environmental record of the petrol giant.
Friends of the Earth energy campaigner Nick Rau said: "Madame de Pompadour was notorious for her ability to influence King Louis. Three centuries later, Esso has gained notoriety for its ability to influence George W Bush in the White House. The arts shouldn't take dirty money from global warming villains like Esso."