Telephone: 020-7636 9098
Address: 57 Cleveland Street, London W1
Open: All week, noon-3pm, 6-11pm (Fri & Sat, 11.30pm; Sun, 10.30pm)
Price: £15-£18 a head, including water and a large bottle of Cobra beer
Wheelchair access

Even from a distance of 25 metres, it was clear that the friend meeting me at a venerable southern Indian place in that part of London grandly known as Fitzrovia was troubled. I watched as he shuffled from foot to foot on the pavement, alternately peering through the window, then up and down the street, like a bad mime artist trying to convey sheer disbelief.

"It's not this one, is it?" he said when I finally joined him. "We're not going to this one?"

Although the name above the door tallied with the one I'd given him, his perplexity was understandable. With its grubby frontage and smeary window featuring fairylights, Ragam is the sort of restaurant to which reviewers seldom take a notebook. You could walk past it 10,000 times without being remotely tempted to enter, even if you noticed it at all. Taking him by the neck, I steered him through the door. The first impression of the interior - gnarled wallpaper, a curious arrangement of floorboards on the ceiling, sepulchral lighting and naive pictures of ethnic scenes and deities - did so little to dissuade him that he was the victim of a practical joke that I toyed with requesting rope with which to tie him to a chair lest he make a dash for freedom when I went to the loo.

"Well, this is, er ..." he said, picking up the laminated menu and glancing again around the room. "It's very, um ... yes, well, here we are."

Horses for courses, to borrow from the Federation of French Brasseries' mission statement: if shabby melancholia isn't your thing, Ragam probably won't be either. Myself, I adore it. There's something about genteel decay that lends itself to reassuring self-pity, much as a decent cold does before it goes to the chest, and I'm never more cheerful than when feeling sorry for myself while closeted in a gloomy restaurant that appears to have been a stranger to Mr Dulux since it opened almost three decades ago.

My friend, on the other hand, took a while to be seduced. The charm and warmth of our waiter, whose dazzlingly white teeth seemed a deliberately ironic gesture given the setting, began the thawing process. The food did the rest. After three mouthfuls of his starter, my friend was besotted. "This is amazing," he said. "Why on earth haven't you brought me here before?"

The shameful truth, for one who's written about restaurants since the reign of Edward VII, is that I hadn't heard of it until a genius in the office made the recommendation. Those of you irritated by the tendency of columns such as this to concentrate almost exclusively on the swanky, the faddish and the wilfully expensive have a point. There is a deeper joy in discovering places such as Ragam, and they deserve far more attention than we give them. Not, in truth, that there can be too many like Ragam, least of all in a city in which commercial rents are often probative. It's hard to see why they'd charge so absurdly little (few dishes, even the meat ones, are more than a fiver) unless this is a labour of love.

"Oh God, this is wonderful," moaned my friend, a vegetarian, as he laid into his dosai, a delicate, flour pancake filled with coconut, vegetables and a brown sugar called jaggery. "This is bliss." My dosai, filled with a gratifyingly chillified chicken massala (clearly not the familiar bottled marinade) was superb, too.

So enormous were the dosai that we could have finished there but, encouraged by the silly prices, we ordered obscenely instead. Southern Indian cuisine is dominated by vegetables, and from the wide range on offer we had bhajis of cauliflower and peas, fried aubergines ("Really nice, really fresh ... moist, in a good way"), mixed veg with sweet chilli, beans and coconut, and delectable green banana. Although the piscine life form in question was obscure, fish curry was rich and strong, and provided the sort of tongue-tingling afterkick that points to freshly crushed spices. Vegetable biriani was impeccable, as was paratha.

This is a magnificent little restaurant, impervious to the march of the high-street tandoori and the trend for posh Indians serving garbage in all-purpose curry sauce. It prefers instead to provide fabulous regional cooking at prices that beggar belief, just as it has done for almost 30 years. Ragam is an absolute, 24-carat gem.