You cannot turn the page in a fashion magazine without seeing an image of a luxury brand. From exquisite diamonds seductively draped over a models neck, to aspirational designer fashion shoots showcasing the latest it-bag and must-have clothes, we are living in an era of surplus luxury marketed to please each of our consumer senses. But how sustainable are these brands?

These days, the big luxury houses have the power to influence consumer aspiration and behaviour by editing our choices through product design, distribution and marketing. However, many luxury consumers are part of an affluent, global élite that is increasingly well educated and concerned about social and environmental issues. These consumers use luxury products as a symbol of success. The definition of success – and the way it is perceived by others – is changing. Many successful people now want the brands they use to reflect their concerns and aspirations for a better world. This is true not only in Western luxury markets, but, increasingly, amongst the affluent middle classes of Asia, Latin America and Eastern Europe.

Given a lack of public information about corporate performance on this agenda, WWF-UK analysed and ranked the ten largest, publicly-traded luxury brand- owning companies on their environmental, social and governance (ESG) performance. These brands include Gucci, Yves Saint Laurent, IWC, Garnier and Louis Vuitton. The ranking is derived from a combination of two types of information: what the companies themselves report to the ethical investment community; and what media and non-governmental organisations have been saying about them. This information was scored, weighted and combined to create a score out of 100, expressed as a grade from A (best) to F (worst). Not surprising, no company was awarded higher than a C+.

The French luxury group, L'Oreal, topped the ranking and the Italian group Tod's came tenth. As reported by themselves and others, the ESG policies and performance of luxury brands is inferior to that of other types of leading brands. Richemont and PPR, whose brands include Chloe and Gucci respectively, are both graded D for their ethical efforts. The report recommends that with their greater budgets, producers of luxury goods could in fact be leading the way in social and environmental performance. Researchers found that in some cases the luxury goods industry, which is worth £77bn worldwide, is depleting natural resources, exploiting labour and hiding its supply chain from outside scrutiny.

Celebrity endorsement of ethically questionable luxury goods also comes under fire in the report, which says that while Hollywood stars such as Sienna Miller are good at raising ethical issues, they do not apply the same principles to the labels they choose to promote. Miller, who has given her face to the Global Cool environmental campaign, also promotes Tod's, the worst offender in the ethical audit.

Luxury companies must do more to justify their value in an increasingly resource-constrained and unequal world. Despite strong commercial drivers for greater sustainability, luxury brands have been slow to recognise their responsibilities and opportunities.

A key impact of luxury brands on sustainable consumption is through its influence on people around the world. The brands promote concepts of quality, style and, ultimately, success. The scale and urgency of the sustainable consumption challenge requires all those who communicate widely, including iconic brands, to promote a more authentic understanding of quality, style and success, which includes respect for each other and the planet upon which we depend.

In reality, the most successful and iconic brands, especially in the worlds of fashion and technology, do not so much respond to consumer demand as create and influence it. Anthony Kleanthous, senior policy adviser for WWF, said: "This report is a call to action for the world's top brands to improve the way they do business. Luxury companies must do more to justify their value in an increasingly resource-constrained and unequal world.