Half a dozen eggs and a bag of cement please

When did you last see a Tesco store? Today, yesterday, whenever it was I bet it wasn't longer than a week ago. Wal Mart's CEO has seent too many. He has called for the Office of Fair Trading to probe Tesco's fast growth. Tesco now has 30.4% of the groceries market, Wal Mart and Sainsbury 16.7% and 15.7% respectively. If the OFT, dubbed Only Fair Tesco by Tesco's rivals, investigates it may decide to curb any further expansion in the grocery market.

As a listed company, Tesco is continually looking to grow. It already accounts for £1 in £8 spent by UK shoppers, and has expanded overseas and into many new sectors such as gas and electricity. But if the OFT restrict future growth within groceries, it will speed its growth into other markets. More impotantly Tesco has made no secret about its desire to build on its non-food sales. It announced two trial stores, to be called HomePlus, to see if its summer success in home furnishings could be repreated on a larger scale. Added to the often forgotten fact that Tesco used to sell a lot of paint, and maybe Builders' Merchants should pay more attention.

Will they stop at home furnishings? Or paint or DIY? It's not hard to imagine Tesco entering the building supplies market under pressure to grow. If it does, acquisitions would be one way in. But they wouldn't just put their name above the door and carry on with business as usual. They know what lean thinking can do, and they apply it to all their businesses. It's a winning formula. There's no reason to think that these core skills wouldn't be effective in building supplies too. Where it's been used it has always worked.

Tesco may not go that far but building supplies must be on its map. The threat to Merhcants from new rivals is real. The threat from new rivals plus new thinking should make us all sit up. But Builders' Merhcants don't have to wait for the threat to materialise before taking lean thinking seriously.