At this week’s City Food Lecture Paul Polman, Unilever’s chief executive, gave a fascinating insight into his company’s long-term strategy to source 100 per cent of its products sustainably within the next decade.

That’s quite an undertaking from a €40bn turnover colossus that sources a significant percentage of the world’s raw agricultural resources. It’s also quite a jump for a company that Polman says currently only sources 10 per cent sustainably.

But it goes to show just how seriously the world’s big corporations are taking the environmental agenda and the need to be seen to be doing the right thing for the planet.

Everyone agrees that consumers want to see companies being socially and environmentally responsible, and anyone not making these issues a high priority could find customers hard to come by.

Crucially, Polman insisted that these goals can be achieved while still increasing crop yields and keeping the cost of the end product down.

There was also much talk at the lecture about the need for higher food prices, but Morrisons’ corporate services director Martyn Jones was quick to warn that retailers will be doing their best to keep a lid on increases.

Instead, Morrisons will be working with producers to bring even more efficiency to the supply chain, he said.

But with many fresh produce suppliers stretched almost to breaking point, it’s questionable how much more efficiency can be squeezed out of the chain before supermarkets - and consumers - have to accept an increase.