The Indian restaurant belongs as much to the London High Street as do Dixon's, the Sock Shop or Marks and Spencer. Is there an adult in this country who does not now know that a Naan is leavened puffy flat bread, or that bhindi is lady's fingers, or that sag is spinach?

In only 50 years it has become an institution to rival the pub and the café. It has seen off the tea-room, the fish and chip shop and even its nearest 1960s rival, the Chinese Take-Away. It is now easily the most popular restaurant in Britain, and our national dish is now Chicken Tikka Masala (CTM). Twenty-three million portions of CTM, as it is called in the trade, are sold in restaurants every year. Ironically, this is a dish unknown in India or Pakistan. When the London Evening Standard sent a batch of frozen CTM to New Delhi for a tasting by Indian food writers and gourmets it was pronounced dreadful by every man jack of them.

In recent years, the Indian restaurant in London has grown up and evolved. It has moved on from the dark red carpet, cheap gold chairs and flock wallpaper that used to characterize it to be more fashionably decorated and certainly more fashionably patronized. Some have even embraced minimalism and the cool colours of New Britannia.

Even more importantly, it has left behind the old "three-pot" cooking system. The old London Indian would have one pot of chicken, one pot of unknown meat and the other of rice on the stove. When an order arrived a packet sauce was added to the right meat which in turn was added to the rice. The curry powder moved it from a korma (that's mild, for strangers to the curry) to a vindaloo (that's take-the-roof-off hot), and vice versa.

These days, the food is frequently as good as any in the city. In the west of London, in Southall for example, there are restaurants that are so exceptional that gourmets fly in from India to eat at them. And in East London, around Brick Lane, the Bangladeshi restaurants produce some of the finest food ever to come out of the jewel of Asia.

But it is not just in small pockets that the great Indian flourishes. In every corner of the capital there is a decent Indian lurking nearby. And no matter to what class, race or gender a Londoner belongs, the Indian and its take-away arm is part of his or her way of life. It is a sign of home. If you need final proof, there is now a fast food Indian outlet at Heathrow Airport to send Londoners off with fond memories (and to welcome them back). Its speciality? Chicken Tikka Masala burgers.