Yet Walmart, Carrefour and Tesco, the world's biggest supermarket chains, gave the recent decision of India's government to open up the retail market only a cautious welcome. “We will need to study the conditions and the details of the new policy and the impact that it will have on our ability to do business in India,” explained Raj Jain, chief executive of Bharti Walmart Private Limited, a joint venture between Walmart and Bharti Enterprises, a local conglomerate. And a spokesman for Tesco said that the company still needs to learn more about the finer points of the reform.

The caution may come as a surprise, but it is justified. Entering a market as big and complex as India's is a big bet, even for experienced international retailers. Success is by no means guaranteed as China shows, the other promised retail land in Asia. Tesco's Chinese operations are only breaking even though they have been in the country for seven years. Walmart is doing better, but this was helped by its takeover of Trustmart, a Taiwanese supermarket. Carrefour and Auchan, two French supermarket chains, are doing best, because they adapted more than their rivals to the taste of the Chinese and their shopping preferences, says Ben Cavender at China Market Research in Shanghai. Carrefour, for instance, introduced what is known as “wet markets” in most of its outlets: open food markets that sell live animals.

To be successful in India, Walmart, Carrefour and Tesco will need to give their local managers a lot of autonomy to adapt their stores. India boasts more than 20 official languages, three major religions and many, very different culinary traditions. Big Bazaar, one of the few Indian hypermarket chains, shows how far such adaptation will have to go. Instead of copying the narrow aisles in Western stores, designed for individual shoppers with carts, the firm has packed its stores with clusters through which shoppers have to navigate. This recreates the organised chaos Indians know from shopping in real bazaars: bumping into people, chatting and eating.

What is more, though the leading international supermarket giants are more than ten times bigger than Indian rivals, their global purchasing power is only of limited use. Selling food is very different from electronics retailing, says Anil Gupta of INSEAD, a business school. Purchasing digital devices, he explains, can be done globally and big retailers are able to squeeze their suppliers. By contrast, food retailers buy from local farmers; even the packaged food they buy from multinational food makers such as Nestlé or Kraft is mostly produced locally. This limits bargaining power.

Since Walmart, Carrefour and Tesco are also likely to face fierce political opposition, it is no wonder that they are hesitating to commit to huge investments in India. They may just continue to expand their existing partnerships. In 2007 Walmart and Bharti established Bharti Walmart Private for wholesale cash-and-carry and supply-chain management. Tesco has teamed up with Trent's Star Bazaar chain to enter the wholesale market. Carrefour has two cash-and-carry stores in Delhi. And Germany's Metro operates six wholesale stores in India and is planning to open up to four new ones.

The retail legislation itself makes it unlikely that Western firms will rush into India, reckons Christopher Hogbin of Bernstein Research. The reform simply comes with too many strings attached, he says: the requirement to have a (minority) joint-venture partner; the obligation to invest in infrastructure; and the condition that stores can only be set up in cities with more than one million inhabitants.

Still, says Mr Gupta, the new legislation is game changer that will improve the lives of farmers and consumers. Those who see themselves as defenders of India's millions of small shopkeepers would argue precisely the opposite. Given the caution of the global supermarket giants, they will have less to shout about.