Asda's food isn't good enough, which is why the supermarket's sales have slowed of late and in the past three months, gone into reverse. That's the view of the retailer's own CEO, Andy Clarke.

It might not seem much of a revelation to long-standing critics of the business. But it still represents a pretty extraordinary admission for a man in Clarke's position.

You can interpret that candour as a no-nonsense statement of intent from a business that's identified a failing and is determined to put it right. Another, less charitable, view would be that Clarke has had a bit of a 'Gerald Ratner moment' just a few months into the top job.

For now, the former take seems more accurate so long as his words are backed up with investment. As they say in rehab, the first and hardest step is recognising you've got a problem.

And while Asda's ­addiction to ­promotions has proved harder to shake off than the supermarket might have expected, Clarke's sobering intervention might just be the push the business needs towards a brave new world.