They say that a good big’un beats a good little’un. But while scale has its advantages, stealth isn’t usually one of them.

Today One Stop – acquired by Tesco via its 2002 swoop for T&S Stores – unveiled a deal to buy 77 stores from northeast indie Mills Group.

Including Tesco Express, the retail giant now has 1,700 convenience stores. And the ACS is up in arms, with James Lowman urging the Office of Fair Trading to investigate.

“The competition authorities have repeatedly failed to grasp the implications of the continuing growth of Tesco’s shadow brand,” Lowman said.

“The OFT allowed the original acquisition by Tesco of over 1,000 stores without adequate scrutiny in 2002 and the Competition Commission failed to address the issue in the two-year grocery market inquiry. They must not make the same mistake again.”

On the one hand, One Stop says it has just 1.2% of the UK convenience market. The ACS argues, meanwhile, that Tesco and its offshoots together represent a whopping 27% of the UK’s convenience outlets.

Last year the association was making similar noises. It pointed out (quite reasonably) that most shoppers don’t make the connection between the two, accusing the supermarket of trying to move secretly into new areas of business.

Mind you, Tesco wanting new business is hardly a revelation of WikiLeaks proportions. The oft-quoted stat that one pound in every seven is spent at Tesco only invites speculation about how it plans to get the other six.

Lowman called for “a full and robust investigation into the implications of the continued growth of the One Stop format”. But judging by the “administrative priorities” recently cited by the regime ahead of its planned consolidation, that prospect seems slight.

Lowman and the small businesses he represents face the reality that the one-stop shop sometimes isn’t very convenient at all.

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