Dinner by Heston Blumenthal, Mandarin Oriental Hotel, 66 Knightsbridge, London SW1

There's a slim chance that a couple of people reading this may have missed the hoo-ha surrounding the opening of Heston Blumenthal's new restaurant, Dinner, at the beginning of last week. Booking lines were swamped, tables booked up until some time in the next millennium, journalists stole in for sneak previews before the official launch, and overnight reviews were splashed by several newspapers– including this one.

So, like a weary battlefield messenger staggering back to base from the front line, only to find that someone has already phoned ahead with all the news, I will assume you already know the basics. That Heston Blumenthal, Britain's most brilliant and experimental chef, held out for years against opening in London, before agreeing to take over the prime space formerly occupied by Foliage in Knightsbridge's Mandarin Oriental Hotel. And that Dinner, only Blumenthal's second restaurant proper, is very much not The Fat Duck 2.0. The cutting-edge scientific techniques and madcap playfulness which characterise both his cooking style and his TV work have been set aside, in favour of a scholarly drilling down into British food tradition. The Mad Scientist has become the History Man.

Never can a grand London hotel dining room have offered a menu of such perplexing unfamiliarity. Big-name chefs in top hotels normally stick to a formula: modern French cuisine, luxe ingredients, tippy-toe service – the international signifiers of the fine dining experience.

You don't get any of that here. A meal at Dinner is a no-fuss experience. Service is friendly and direct. The super-sized dining room, all dark wood, unclothed tables and low banquettes, is relatively unswanky. And the menu is a startlingly original read, offering new versions of ancient British recipes, reworked with all Blumenthal's customary invention. Salmagundi, savoury porridge, turkey pudding with cockscomb, cockle ketchup, taffety tart – God knows what non-Anglophone diners will make of it, or the reading list printed on the menu, giving historical sources for all those historical sauces.

Lunching on the day after Dinner opened – well, we wanted to give it time to bed in – Mark Hix and I soon realised that despite its historical roots, the food at Dinner is absolutely of the moment, and much less weird than it sounds. Here is the missing link between the labour-intensive complexity of contemporary haute cuisine, and the produce-led simplicity of modern British pioneers like Fergus Henderson and Mark himself. "Simple sophistication" is how Mark characterised the style.

His starter, from the £28 set lunch menu, wouldn't have been out of place in St John; a lip-sticking "ragoo" of pig's ears, slow-cooked with onion, and slathered on to hunks of chargrilled bread – a remarkably down-home dish to be eating in a grand hotel. My own starter, the savage-sounding "rice and flesh", turned out to be a fashion-plate of a dish, in which glossy mouthfuls of braised calf tail posed on a luscious, vividly yellow risotto, stippled with saffron and pleasingly acidulous.

Heston's historical tour has revisited some of his own history, too. A main course of duck leg, deboned and cooked sous-vide, then glazed in honey and spices, may have been inspired by a recipe from 1672, but wasn't that far from the hammed duck legs he perfected in the early days of the Fat Duck. Spiced pigeon, also cooked sous-vide, and seasoned with spiced salt, was a perfectly-pitched plateful, the sweet, pink meat partnered with wonderfully smoky artichokes in a heavily-reduced ale sauce.

Side dishes, at £4 each, included perfect, slim French fries. "Just like McDonald's," as Mark said approvingly, dipping one into his silky pommes purée. The much-imitated triple-cooked chips are also available, but only if you order steak (or charm the ladies at the next table, as Mark did).

Apart from the already-legendary Meat Fruit – chicken liver parfait disguised as a perfect-looking mandarin – a disorientating, but utterly delicious, sight-gag of a dish, there was nothing Willy Wonka-ish about anything we ate, no foams or liquid nitrogen. Certainly nothing to frighten the horses, which can regularly be seen trotting around Hyde Park, through the huge picture windows which dominate the room. Sightlines are good– we could see all five of the restaurant critics lunching at the same time as us – and head chef Ashley Palmer-Watts and his team are on full display in the open kitchen, with its clockwork-driven reinvention of a Tudor spit.

From that spit, slow-roasted pineapple, caramelised to sweet intensity, accompanied an ambrosial 19th-century version of bread and butter pudding, Tipsy Cake – another break-out dish that probably already has its own Facebook following. Mark's chocolate bar, a sleek finger of dark, shiny ganache concealing passion fruit and ginger jam, confirmed that even the more apparently conventional dishes have been endlessly worked over and refined.

When the hyperbole and hysteria around Dinner subside, it will be clear that while it may not be "the best restaurant in the world", as one over-excited critic has anointed it, it is certainly a world-class restaurant, which takes British food to another level. It offers the perfect big-occasion option for people who want to enjoy dazzling food and wine without all the five-star fuss.

"This could change the face of poncey dining," as Mark put it, with characteristic unponciness, before concluding that it was the best meal he'd eaten in the past two years. It's only a shame that it will probably be another two before the next table is available.

Dinner by Heston Blumenthal, Mandarin Oriental Hotel, 66 Knightsbridge, London SW1 (020-7201 3833)

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