Jamie Oliver's Diner, Piccadilly

Taking "inspiration" from an existing successful business is not, in itself, evil. Noting the success of Bubbledogs and the Big Apple Hot Dogs and then opening your own hot dog stall is not evil. Spotting the crowds in MeatLiquor and opening your own burger and cocktail joint is not evil. Being envious of the queues trailing down Beak Street from FlatIron then serving your own version of the dish is not evil. Wanting to get in on the market for slow-cooked BBQ ribs pioneered by Pitt Cue is not evil.

But doing all this at once?

It's not just that Jamie's Diner is cynical. It's not merely that it's an incoherent, paper-thin mess of a place that shouldn't have left the drawing board. It's way more than that. It's a multi-million pound cliché warehouse, a jumble of every single one of London's food fads all piled up on top of each other, each more disastrously "reimagined" than the last.

The menu is bone-jarring, multi-car pile up, so much so that pointing out all its failings would take a short novella never mind a blog post. There's a collection of "starters" of no obvious geographical origin, "cajun" prawns and "sweet potato quesadilla" jostling somewhat uncomfortably next to a Marie Rose prawn cocktail. There's a box of four "Classic Dishes" including a Reuben sandwich, a £15 chicken in a basket (one would hope you get the whole chicken for that; I bet you don't) and the worryingly singular "Giant Spaghetti Meatball".

There's another section for "salads" which has so many eye-twitchingly irritating phrases I got as far as "Super Duper Quinoa Salad" then gave up and moved on. The "Steaks" section has just two choices - a £16.50 "Flat-Iron" (for all its failings, at least Flat Iron Soho's is only £10 with a salad) and a completely bonkers "Rib-eye for two" for £60. There's a section for "waffles" which has only two choices; one with pulled pork and one - I swear I'm not making this up - with smoked salmon and horseradish cottage cheese which must rank with one of the most terrifying ideas anyone in charge of writing a menu has ever had. There's also a box for "burgers" where if you really want to push the boundaries you can specify extra sweetcorn salsa, gruyere cheese and piccalilli for £1 an item.

But if the menu is a car crash, just wait till you get a load of the food. "Guacamole tortilla chips" were notable insofar as they contained no tortilla chips, and very little guacamole, just some salty water biscuits of some kind, slowly dissolving under a pile of tasteless chopped tomatoes. They were served in a sort of bucket thing with a handle which I'm sure someone thought was a good idea.

"Dirty Barbecue Ribs" were burned, so it's hard to objectively rate their "dirty"ness, although if "dirty" means "sickeningly sweet and overcooked" then we're probably halfway there. A pile of chopped carrots and cabbage and who knows what else was entirely unseasoned and served no purpose, although bizarrely shoestring fries were crisp, perfectly seasoned and actually rather nice.

Worse was yet to come, though. "Giant spaghetti meatball" was, in fact, three or four totally normal-sized meatballs of flavourless mystery meat, nestled amongst slimy commodity pasta. They were garnished with sour cream, cheap parmesan and chopped parsley, the latter being all you could taste. "It smells like vomit," my friend pointed out thoughtfully, as she gamely prodded her way through it.

Dear God though, the pulled pork waffles. At first I couldn't remember if I'd ever tasted pulled pork quite this bad, and then it dawned on me - I had. At Jamie Oliver's other restaurant, Barbecoa. A winning combination of dry, sickly sweet and sloppy, their sugared-vinegar runoff had turned the waffles below from what were once presumably very bland but inoffensive carbohydrate into soggy, tooth-softening mush. Awful, and yet some deep-fried chillis, although slightly chewy, were genuinely tasty, with a gentle citrus tang and moderate heat. Which didn't go anywhere near redeeming the dish, just made the whole thing that much more psychologically bewildering.

Staff were enthusiastic - and numerous - but had a slightly eccentric habit of asking how everything was every five minutes, and given the amount of trauma involved in explaining the difference between beer and ginger beer to my eastern European waitress (a lot), I didn't feel like doing anything other than grunt "fine thank you" on each occasion. But what could they have done, anyway? Re-done the 12-hour pulled pork? Re-trained the chefs? Burned ribs aside, none of the food was cooked wrong, it just was wrong.

For all the grumbling about trend-chasing, and there has been a fair amount of grumbling (most of it from me), it's worth pointing out that however unimaginative a concept, when the food is decent, much can be forgiven. Clockjack Oven may have been rushed into field on the back of the success of Chicken Shop, but given that it's also serving lovely moist chicken and crunchy double-cooked chips for less than a tenner, who cares. And although it's tempting to blame MeatLiquor for BRGR, Burger and Shake and who knows how many other bland ripoffs, we can also thank them for Patty & Bun, Honest Burgers and Lucky Chip, all of whom London would be much poorer without.

The food here is terrible, but Jamie's Diner is enraging - apocalyptically, biblically enraging - because it has no ambition greater than to make some easy money off the back of the hard work of others, by scraping every barrel of London's current American comfort food fashions, and to exploit passing tourists and Jamie fans and get them out of the door before they realise they've been scammed. And if anyone else had put their name to this giant con trick, it would be criminal enough. But for Jamie Oliver, who has made a living for years out of telling poor people not to eat burgers, hot dogs and chips only to then charge way over the odds for the same food as soon as he realises there's money to be made, the nerve is astounding.

We are led to believe that Jamie's Diner is a "pop-up". We know this because it says 'POP-UP' on every menu, and it's plastered all over the walls and windows. In fact, the lease on the building is 3 years, which as anyone in the industry will tell you, is a perfectly acceptable period for a restaurant to last. The only way anyone would call their 3-year restaurant a "pop-up" would be if, not content with having ticked off nearly every other London food cliché, they wanted to jump on that bandwagon as well. And the cynicism, the lack of originality, the shallowness, that is all irritating enough. But to perform a volte-face on your own multi-million-pound-earning healthy-eating campaign to make yet more millions? That's shameful.

1/10