Most of the conventional restaurants at Westfield are on its edge, at ground level in the “Southern Terrace”. There’s a different set-up at its heart, if it has a heart. In “The Balcony”, overlooking the giant atrium, there are “13 fully licensed culinary counters”, as the Westfield management puts it, “where open cooking brings drama”, don’t you know.

The “international food concepts” include a salad bar (Tossed), Vietnamese (Pho), Indian (Tiffinbites), Chinese (Bamboo Basket), Middle Eastern (Comptoir Libanais), Italian (Ooze Risotteria) — and, most remarkably, south-west France in the shape of Croque Gascon.

At all of these, you’re eating on the hoof. You collect your food on a tray and find somewhere to eat in the shared seating. Here you can eat as little or as much as you want — or, to put it another way, it’s a lot of scraps and samples, an invitation to browse as many forms of cooking as possible.

Those styles of cooking that are basically street food already are obviously suited to this approach. To my mind, about the furthest you can get from street food is the cuisine of south- west France, where the bells ring at noon and everything stops for three hours. They think only animals eat standing up (they are right).

It is easy to see how Pascal Aussignac and Vincent Lebeyrie arrived at the concept of Croque Gascon. Since opening their excellent main restaurant in Smithfield, Club Gascon, they have found ways to make their food more accessible, first through their winebar, Cellar Gascon, and then by serving great moderately priced food in their shop, Comptoir Gascon.

Croque Gascon is a step too far. It didn’t help that on the evening we went, most of the cooking was poor, much too heavy-handed on the grill.

Grilled scallops and milla chips (£9.50) delivered three over-seared scallops, sitting on rocket and tomatoes dripped with basil oil, accompanied by hefty, dry polenta chips. Sautéed baby squid with chilli and crunchy greens (£7.50) was another small serving, the fresh squid not much enhanced by mangetout and some fennel, all overheated with chilli.

French fries, cooked in duck fat though not tasting much of it, were just about OK — again a little dry, not the crispy treat that potatoes sautéed in duck or goose fat should be. They were cheap enough, though, at £2.50.

“Duck Burger Signature” is the most expensive plateful at £14. An over-toasted bun came with a meaty minced-duck burger, cooked pink but still heavy and not very flavoursome. It sat on a chilli-tomatoey sauce with a bit of lettuce and some slices of sweet raw onion. Crowning the lot was a slice of delicious pan-fried duck liver, crisped on the outside, melting and complex on the inside, the highlight of the meal, demanding to be eaten on its own. For this micro treat, however, £6.50 more is charged than for the plain duck burger.

Piperade Basquaise (pepper stew with a fried egg on top, £5) was a surprising failure. The peppers were overwhelmed by the tomato sauce, overcooked and oversweetened into a jammy substance that had a high initial impact but proved unfinishable.

There is a short list of appealing wines but they are not cheap (basic Fronton rosé, £19 a bottle; a tannic Madiran Labranche Laffonte, £21.50 a bottle; the cheapest glass is a Plaimont white at £4 for 175ml) and vintages aren’t specified. It makes a big difference in this region.

I found the whole experience dismal. Westfield is a great hubbub and the seating, although otherwise luxurious — leather banquettes, bling marble-topped tables — doesn’t offer any sheltered place to eat. You feel as though you are in the largest airport terminal in the world, from which there is no escape because they forgot to build the runways.

Perhaps the best thing to do is embrace the show and get a seat on the balcony overlooking the atrium — even so, it wouldn’t be this food I’d choose to graze on there.