It was only six stores, but for Tesco every little helps.

The supermarket chain yesterday achieved a significant milestone on its road to retail domination, with the announcement that it is to have a superstore in every corner of Scotland.

The Northern and Western Isles held the last three of Scotland's 16 postcode areas without a Tesco superstore. Yesterday, they, too, found they could no longer resist the strength of the Tesco embrace.

The purchase of stores in Lerwick, Kirkwall, Stornoway and Ullapool, added to two other Somerfield sites, in Wellington Road, Aberdeen, and East Lane, Paisley, meant the final pieces of the jigsaw were in place.

Now only the Harrogate postcode in England is officially "Tesco-free" in the UK, as the chain decides whether to continue with plans for a 107,000 sq ft store in the Yorkshire town.

There had been moves in Shetland to launch "a keep Tesco out" campaign because of fears that it would buy a site on the outskirts of Lerwick and suck much of the commercial activity out of the town centre. However, there was some relief yesterday at the company's strategy for the islands.

Alistair Carmichael, the Liberal Democrat MP for Orkney and Shetland, was to have spearheaded such an opposition campaign and yesterday requested an early meeting with Tesco to discuss local concerns. But he added: "My initial reaction is that the purchase of an existing supermarket on an existing site is probably preferable to the construction of a new supermarket on an alternative site."

Liam McArthur, LibDem MSP for Orkney, also sought assurances for his community.

"A thorough strategic review is currently under way to the challenges facing Kirkwall town centre," he said. "It will be important to establish early on what Tesco intentions are in taking over the Kirkwall Somerfield site, hopefully an early meeting with Tesco representatives will enable Alistair and I to establish greater detail about their proposals and outline local residents and business concerns."

Meanwhile, on Lewis, observers of the strong Sabbatarian tradition were reassured by the news that Tesco would make Stornoway the company's only superstore not to open for at least some of Sunday. Those tired of the Hebridean Sabbath were not so pleased.

But most islanders will welcome the chance to shop locally at the chain which began in 1919 when Jack Cohen opened a grocery stall in east London. Five years later the Tesco name emerged for its first branded product Tesco Tea - TES from TE Stockwell, a partner in the tea suppliers and Co from Cohen.

Its hold in 21st-century Scotland continues to surprise.

According to Professor Leigh Sparks, of the Institute of Retail Studies at Stirling University, not since the Co-operative in the late 1950s and early 1960s has Scotland seen such retail dominance.

"The Co-op's market share was even higher than Tesco's with something like 20% of the entire market while people talk about Tesco having one in eight or around 12%.

"But you have to remember the Co-op was a movement made up of many hundred small independent societies with members. It wasn't really one organisation.

"However I can't think of any other organisation that has been so dominant until today's Tesco.

By numbers ...

1200 Number of Scottish farmers supplying Tesco with beef.
2 Number of new Tesco stores every week in the US.
250,000 Number of staff employed by Tesco in the UK.
1900 Number of Tesco stores in the UK.
31.4% Market share of Tesco.
93 Stores in Scotland.
25.9m Square feet of sales area in the UK.
1117 Amount in pounds that Tesco made each second in the UK for the 26 weeks to August 26, 2006.
80% Percentage of Tesco profits coming from the UK business.
11 million Active Tesco Clubcard holders.
12 Number of countries outside the UK where Tesco operates.
2672 Number of Tesco stores across the world.
389,000 Number of staff employed by Tesco worldwide.