They are global brands, yet few people would have any difficulty identifying their countries of origin. There are several corporations with a global presence, but we have yet to see the emergence of the global corporation.

What would a global corporation look like? Philip Condit, chairman of Boeing, the US aircraft manu-facturer, ventured a definition in an interview with the Financial Times in 1997. Being a global company meant that, wherever you operated, people thought you were a local company. "I believe we are moving towards an era of global markets and global companies," he said. His role model in this regard, he said, was BP.

"BP is probably the most global company in the world. It is interesting to see that in the US its nationality has begun to disappear. Almost everybody in the US says BP and not British Petroleum. It is a local kind of company." Mr Condit set himself a goal: within 20 years, people outside the US would no longer think of Boeing as an American company. Four years later, that goal seems as far off as ever.

Boeing is not alone in still being strongly associated with its country of origin. Cast an eye down the list of the world's 50 most respected companies, published in the FT in December. General Electric of the US is in first place, Microsoft (US) is in second, Sony (Japan) is third, Coca-Cola (US) is fourth, IBM (US) fifth, Toyota (Japan) sixth. They are all global companies, with resolutely national identities.

It is only when you reach 12th place that you come to a company whose nationality is more difficult to define: DaimlerChrysler, the product of a 1998 merger between German and US companies. But even Daimler- Chrysler is not a global company. Originally presented as a merger of equals, it has since turned into a troubled, German-dominated group, and several of the key US executives have gone.

There are other, more settled binational companies on the list: Royal Dutch/ Shell and Unilever, two long-standing Anglo-Dutch groups, and ABB, the Swiss-Swedish engineering group. There is also BP, which many, like Mr Condit, believe has transcended its British background.

Further down the list of most respected companies is Airbus Industrie. The European aircraft manufacturer is a genuinely multinational group, formed from French, German, British and Spanish companies. But Airbus is European, rather than global, and nationality still plays a strong role in who runs it. Its headquarters is in Toulouse and the French have long regarded the position of chief executive as one to which its nationals have an automatic right.

Yet many business trends appear to be pushing companies towards being more global: liberalised trade, the spread of the English language, the internet and satellite television.

So where are the global companies? John Lindquist, a London-based senior vice-president of the Boston Consulting Group, believes he works for a global firm. Although, as its name suggest, BCG was founded in Boston, it now has more partners outside the US. It also generates two-thirds of its revenues outside the US.

Mr Lindquist says that McKinsey, BCG's rival consulting firm, is also global. They are both meritocratic organisations, where partners can rise to the top regardless of nationality. Yet he does not deny that there is still something distinctively American about consulting firms such as BCG. "There are some American cultural characteristics - for example, the openness and the pace of decision-making. There's obviously an American stamp."

Outside professional services firms, however, academics who have been studying the idea of the global corporation say that it has proved to be elusive in practice. "For a long time I believed in the emergence of the global company. I'm a little more sceptical now," says Julian Birkinshaw, assistant professor of strategic and international management at London Business School.

One of the reasons the global company has failed to emerge is the complexity of trying to manage one, Mr Birkinshaw says. DaimlerChrysler's experience shows how difficult melding even two nationalities can be.

The story of Pharmacia & Upjohn, the pharmaceuticals group, provides another illustration.

Formed through the 1995 merger of a US and Swedish company, Pharmacia & Upjohn decided to base its headquarters in a neutral country, the UK. It had operational and research and development facilities in the US and Europe. It did not work.

The various centres turned into fiefdoms. Eventually the group moved its headquarters and research and development centre to New Jersey. The company has since been taken over by Monsanto of the US. It still has worldwide operations, but its base is the US.

But this does not mean, Mr Birkinshaw warns, that companies can afford to retreat into narrow nationalism. Large companies do have markets around the world - and employees who know their local customers better than head office does. "The worst mistake you can make is assume that you have all the answers in your own country," he says.

He points to the example of the Swedish subsidiary of Datacom, a US minicomputer manufacturer. Datacom was struggling with its product line in the early 1990s, and the Swedish subsidiary was on the verge of bankruptcy. The Swedish management turned the subsidiary around by offering service contracts on competitors' products. The US headquarters objected, but the Swedish managers persevered and succeeded.

Ideas from people of diverse backgrounds are vital if an international company is to succeed. But the employees in other countries should not forget they work for a company of a particular nationality. The global corporation is still some way off.