It's remarkable that the current economic climate has coincided with powerful and effective plays from all the big four when, in the boom years, so many were so hopeless for so long, says Adam Leyland

Our annual exercise in quantifying power (see Power List 2009, p42) isn’t easy. And this year’s Top 10 list of multiples was particularly challenging. One might expect the recession to act as a Darwinian exercise in natural selection. Yet the remarkable thing about the current economic climate is that it appears to have coincided with strong power players at all the big four. When Tesco (profits: £3.1bn) is talked of as the weakest performer, you know something extraordinary is happening, as if the planets have collided in a once-in-a-million event.

One can make a case for elevating each of the big four CEOs above their planetary order. Sainsbury's CEO Justin King could come higher, based on the reported size of his bonus, or his supermarket’s unexpectedly strong response – given its more upmarket profile – to the downturn; not to mention the bargaining power he appears to have – on both sides – as the obvious heir apparent to Sir Stuart Rose at Marks & Spencer.

Then again, Marc Bolland has a very strong case, with the latest TNS and Nielsen market share numbers this week showing Morrisons is ahead of its rivals on like-for-like sales growth. Everyone predicted that like-for-likes would get harder the second time around, but not a bit of it.

With all the big four performing strongly, then, the obvious solution is to list the CEOs of the major multiples by planetary size. But as well as being boring, that wouldn’t do justice to the battle plans that supermarkets (not to mention wholesalers and even local convenience retailers) draw up, and the impact these players are having on the grocery solar system.

Which is why Aldi’s Paul Foley has driven a great big wedge through this year’s list. The latest TNS figures out this week suggest growth at the discounters has slowed. But Aldi is orbiting in the same solar system, and forcing bigger rivals to change their course with unpredictable results.