A passerby was overheard this morning giving directions to one of the small army of journalists and retail experts heading to the revamped Tesco Extra in Watford: “You can’t miss it,” he said, “it’s the biggest shop in the world.”

The drastically redesigned 80,000sq ft store might not be that but it certainly feels a world away from anything we have seen from Tesco before.

This feels like the moment CEO Philip Clarke’s promised store fightback gets serious. With a fresh food department to give any of its rivals something to worry about, and an airy upmarket feel to the store throughout, the Watford Extra has the wow factor Tesco’s boss has been seeking.

Clarke promised “destination stores” that would give shoppers a new reason to visit Tesco now that the online revolution has made its big sheds white elephants. A giant giraffe first greets visitors to the store, totem of its new restaurant chain, which sits, for the first time, alongside Harris + Hoole’s classy coffee shop and the high-quality Euphorium bakery.

This line-up looks set to prove a few critics who doubted Tesco’s investment in these businesses wrong. Even better for Tesco, there is plenty more to admire. Highlights include the City Kitchen area where customers can create their own meals for £4, or have a freshly prepared pizza ready in three minutes. Indeed, there are plenty of opportunities to try food, encouraged by the use of Tesco’s Love Every Mouthful branding, which, it would seem, has taken over from Every Little Helps in prominence.

As for non-food, the beauty, health & wellbeing, and baby departments stand out, while the F&F store is quite different from the mezzanine nightmares of the past – it’s a store within a store.

On general merchandise it is obvious Tesco is still uncertain of what will fit in the store of the future, but putting the focus on food-related goods isn’t a bad start.

So there is much for Clarke to be pleased about. The still unanswered question is whether all this is scalable and whether it will blow a hole in Tesco’s budget.

To revamp the 50 Extras as big or bigger than Watford would surely dwarf the £1bn set aside so far and it has another 200 smaller hypermarkets to consider – not to mention the rest of its estate. Yet Tesco bosses claim that everything on show today is both scalable and affordable. If they are right, the gauntlet is well and truly thrown down for its rivals – Asda in particular.

The big winner in this is the consumer, with the good folks of Purley and Coventry next in line to experience Tesco’s new formats on their doorsteps – albeit with different models, we are told. If Tesco can make this the shopping experience for all or most of its shoppers, they and Clarke really will enjoy the results.