The Red Fort 77 Dean Street, London W1

The food is impeccable, the decor and location spot-on – so what could possibly go wrong at this Soho institution?

Do you remember that advert which said that Carlsberg is so good the Danes hate to see it leave? Well, I think that the staff at The Red Fort must feel similarly about their food. What comes out of their kitchen truly is exceptional. They just really don't seem to want us to have it.

It's unfortunate, because this upmarket Indian has been doing a good job of getting Soho salivating ever since it first opened in 1983. Near to the Groucho Club, a trendy clap clinic and the Coach & Horses (once home to Norman Balon, the "rudest landlord in London"), it is so much a local institution that, after a fire there in 2001, the Labour MP Keith Vaz helped to raise money for repairs. He knows it fondly as "the New Labour Canteen". So that explains the size of their expenses...

The Red Fort recently reopened following another Soho fire last summer, so I want to pile in before anyone else leaves a pan on. We book a table for 9pm on a Monday, and arrive three minutes early and hungry. It certainly looks good, with a friendly door-wallah, brown-silk walls, a black-slate water feature, and a mostly shirt-sleeved, male clientele.

But our table is 25 minutes delayed – how about a drink in the bar first? We do as we're told, but we can't help but wince when the bill for two gin and tonics comes to £16.95, including a 13 per cent service charge. Service charge? At the bar? Even Mr Balon never went that far.

Unfortunately, an automatic 13 per cent service charge is not necessarily a guarantee of great service. It's not so much the little things: I'm used to asking for the wine list and seeing it given to my (male) date. I am even (get me) used to a wine list that starts at £25 for an OK shiraz. It's more the slightly bigger things, such as the waiter walking away when I start talking. Or telling me, when I enquire about beer, that "You will not find any beer on the wine list. Tut. It is a wine list."

Given that the beer ("It is an Indian lager called Kingfisher," deep sigh, roll of the eyes) comes by the half pint and apparently costs £4.50, we go for a £32 Berton Reserve Shiraz 2006, which turns out to be a 2007 when it arrives. "The 2006 fire did not affect south Australia," responds the waiter, as if to a pestilent child. It's actually rather nice, when he finally lets us have it. But first, he pours us an inch each, takes away the bottle and hides it on a high shelf. "You want the wine on the table?" he asks later, as aghast as if we had asked to drink it from his pants.

The menu is brief and well thought out. (Although to my mind there are too many dishes "tempered with" and "laced with" things. "Laced with" is redolent of arsenic, is it not? Though at this point I wouldn't be surprised.) Quality British ingredients are given an authentic Indian treatment, as in khargosh achari (rabbit laced with mustard, tempered with fennel and onion seeds, £18). I am assured that the chicken is free range, so I choose the murgh tikka, spiced with ginger, garlic and chilli (£7), and my date has the monkfish tikka (£10). The latter is too overwhelmed with chilli for my fellow diner's sensitive palate, but to me it tastes like barbecued kebabs might taste in heaven: subtle, fresh and with just enough chilli kick. It could do without the banana sauce (on the side), though.

Our mains, in their cute little clay pots, are just as exceptional. The Hyderabadi bhuna gosht (Herdwick lamb with ginger, garlic, black pepper and coriander, £18) is dark and complexly tasty. The nalli rogan josh (lamb shank with nutmeg, cinnamon and bay leaves, £18) apparently "falls off the bone – in a good way", rather than wetly or mushily – and tastes pleasingly of lamb, complemented by spices. A panchrangi dal (£6) is more exciting than lentils have any right to be; but the palak ki katli (£6) is bizarrely dry for spinach. And £5 for plain, boiled rice? Surely people only eat rice because they are too poor to afford real food? We're lucky: a larger group nearby is told that nobody may individually order rice or bread, but that the waiter will bring a selection "for the table".

For fear of having to take out a bank loan, we share a dessert, a sweet, fool-like raspberry shrikhand at £6, and ask nervously for the bill and a cab. The former is £127.69 (plus the G&Ts); the latter asks for £15 to Waterloo station. We walk there, instead, and resolve on the way to eat at the local Indian next time.

6/10

Scores: 1-3 stay home and cook, 4 needs help, 5 does the job, 6 flashes of promise, 7 good, 8 special, can't wait to go back, 9-10 as good as it gets

The Red Fort 77 Dean Street, London W1, tel: 020 7437 2525 Lunch and dinner, Mon-Fri; dinner only Sat-Sun. About £130 for dinner for two, including wine

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Reviews extracted from 'Harden's London and UK Restaurant Guides 2010'. www.hardens.com