Q: What do Rwanda, Yemen, Palestine, Cambodia and Fiji have in common? A: They all want to fly the Commonwealth flag

Far from being a ragged remnant of the British Empire, the organisation is fast becoming an influential player on the world stage, writes Paul Vallely

It is perhaps the most singular legacy of the long retreat from Empire. When Britain pulls out of Hong Kong at the end of the month this largest of our remaining dependencies, since it is not to become an independent state, will be ineligible to join the Commonwealth. At the same time the decidedly un-British state of Rwanda is lobbying to join, as is Yemen, which at least contains the former British protectorate of Aden. The Palestinians have indicated that they, too, might apply to join, if and when they become a sovereign state. And Fiji, suspended after the 1987 coup there, has approached Commonwealth officials about not only rejoining but abandoning its status as a republic and, uniquely, petitioning the Queen to reassume her role as monarch.

And that is not all. There is talk that Nigeria, which after the coup in Sierra Leone has been posturing, without a trace of irony, as the defendant of democracy in West Africa, may be expelled from the Commonwealth at the heads of government summit in Edinburgh later this year for its continued contempt for democracy and human rights.

The eight members of the Commonwealth Ministerial Action Group on human rights, which was set up last year following the Nigerian military regime's execution of the dissident Ken Saro-Wiwa, along with eight other activists, is becoming impatient. The group, led by Nelson Mandela - who swiftly brought post-apartheid South Africa back into the Commonwealth fold - has backed away from the idea of economic sanctions against the country for fear that the Americans, French, Chinese and Russians would not come on board. But it is now considering expulsion for its continued flouting of Commonwealth demands.

"The Commonwealth is taking on a new visible life," says Andrew Porter, an imperial historian at King's College, London. "And for good reasons of self-interest. You might not set it up if it didn't already exist, but it's there and it can be mobilised and its networks used to promote the interests of what is now a quarter of the world's population."

It is an odd business for those who regard the Commonwealth merely as some ragged remnant of Empire, a hangover from the days when pennies were struck with the image of George VI as Emperor of India. "It has helped us come to terms with Britain's decline as a great power," says Porter. But there is more to it than that. "It is difficult to think of any other empire which has left this kind of international organisation behind it." Significant contacts are maintained between the former French colonies and metropolitan France, but they are designed to be much more of benefit to Paris. "Britain doesn't dominate as France does the Francophonie," says Porter. "It's not an Anglo-centric organisation".

It is not even entirely an Anglophone one now. In 1995, the first non- English speaking country, the former Portuguese colony of Mozambique, was admitted on the same day that Nigeria was suspended. Insiders say it was the price which Mandela exacted in return for taking the lead on Nigeria from the white Commonwealth states, who were reluctant to push the matter for fear of charges of racism.

The success of the institution is clear from the queue to join. Motives to do so vary. Sentiment seems to be what lies behind the Fijian request for re-admission. General Sitiveni Rabuka, who led the 1987 coup, has been pressed into negotiations by a groundswell of his own people, who continued to celebrate the birthdays of the Queen and other royals, and whose students continued to apply for - and receive - scholarships from the 1100 Commonwealth awards made every year.

By contrast, cunning self-interest lurks behind the urge of the elite in Rwanda to join. Many observers detect a Tutsi plot behind the move. The Rwandan rulers are English-speaking Tutsis who were previously exiled among fellow Tutsis in neighbouring Uganda; joining the Anglophone Commonwealth would subtly consolidate their position over the French-speaking Hutu majority they now control. Elsewhere, in Barbados fervent republicans campaigning to ditch the Queen as head of state are none the less anxious the island should remain in the Commonwealth.

The formula for that is well-established. Half of the current members are now republics, under an ingenious formulation whereby the Queen ceases to be monarch but remains as head of the Commonwealth. It is no longer the British Commonwealth. The qualifying adjective was dropped in the late Forties to allow India to remain in the white man's club - of Canada, Australia, New Zealand, South Africa and Southern Rhodesia - after its independence as a republic. (Ireland dropped out only weeks before the prescription came into force.) The imperial residue was further dissipated in 1965 when Britain gave up the permanent chairmanship and an independent secretariat was set up making the organisation, which then had 21 members, more difficult for London to manipulate.

Evidence of that lack of malleability was disclosed recently when the first confidential Commonwealth papers were released under a 30-year secrecy rule. During the row over the Unilateral Declaration of Independence by Rhodesia's white settler regime, the Commonwealth came close to falling apart. London insisted on economic sanctions to end the crisis while black Africa demanded that Britain send in troops. At one point the British prime minister, Harold Wilson, pointed out that all the countries at the table had gained their independence from Britain but were now overlooking the fact that Britain, too, was independent. Other members were treating Britain "as if it were a bloody colony". When the other prime ministers protested vehemently and asked him to withdraw the remark, Wilson, the minutes show, said: "All right, I withdraw the word 'bloody'."

There was a time when it seemed the Commonwealth would wither on the vine of Britain's increased involvement with Europe. In the years after the war the notion of imperial or Commonwealth trade preferences was still considered viable. But by the Sixties, Britain began to feel it could not afford to be tied in with economies which were not among the most vigorous in the world. Cheap New Zealand lamb and butter were not sufficient recompense for exclusion from the Common Market being set up in Europe.

In the early days Wilson tried to have it both ways, asking for admittance to the Common Market with a tariff-free zone that would remain open to the Commonwealth and the developing world, and which would not artificially raise food prices. He reckoned without the intransigence of General de Gaulle, who vetoed the application. It was only, in effect, by dropping all its objections that Britain was admitted in 1972, accepting both the Common External Tariff and the Common Agricultural Policy - and additionally surrendering its fishing grounds, something which the other members previously would not have dared to demand. Not long after the trade preferences went, UK visa requirements were introduced for Commonwealth citizens.

If entry into the Common Market hugely damaged relations with the white Commonwealth, it was the intransigence of Margaret Thatcher over sanctions against the apartheid regime in South Africa which placed the greatest strain on relations with black members.

During the Thatcher years it repeatedly looked as if the Commonwealth would be allowed to atrophy by an imperious British prime minister who would brook no contradiction from former colonials.

Commonwealth leaders routinely outraged her. Much influenced by her businessman husband Denis, she embraced dictatorial African leaders like Moi in Kenya and Banda in Malawi, and adopted a pro-Buthelezi and anti-ANC line in South Africa. At one Commonwealth conference in Vancouver she compared the ANC with the IRA, myopically ignoring the difference between the violence of a violent minority outvoted in a democratic country and that of a disenfranchised majority inside a repressive state. Such attitudes, along with her decision to abolish education subsidies for overseas students, led to widespread disillusion with Britain. At one point there was talk of moving the Commonwealth Secretariat to Toronto. The rifts were healed only by diligent back-room diplomacy by the Queen, as Ben Pimlott's biography of the monarch reveals.

Yet the institution survived all this for a number of reasons. It creates an unparalleled forum in which the prime ministers of 52 states have direct personal contact with one another, often without any officials present. Because it is not a strategic alliance or a trading bloc it has no common defence or economic policies. It is a forum rather than a united front, where consensus rather than voting are the modus operandi.

"That may well be why it may be on the threshold of new influence," says Dr Alan Sked, the international historian at the London School of Economics who is a vigorous campaigner for UK independence from Europe. "Regional trading blocks are a chimera; by the 21st century all competition will be between firms, not countries." And, he says, it lacks the pomposity and posturing of the United Nations.

"It is a comfortable form of international co-operation where people can talk confidentially without feeling threatened," says Peter Lyon, head of the Institute of Commonwealth Studies at London University. "It hasn't got a centre or a periphery. All have equal status."

It is a model which extends from meetings of prime ministers to the wide networks of informal association: there are Commonwealth associations of dentists, tax gatherers and parliamentarians, as well as meetings of foreign, finance, health and education ministers. Co-operation is the byword of its development programmes, with aid from the industrialised members often being used to finance the transfer of skills from one Southern country to another. "For countries with a population of less than half a million it is probably the most useful international forum they have access to," says Peter Lyon.

Fear of jeopardising that is what will stop the Commonwealth expanding too wildly. "Smaller members fear the sense of intimacy will be lost," says Andrew Porter. (An approach from Cambodia has been politely rebuffed; and suggestions that Ireland might rejoin as part of the Ulster peace process have foundered on the fact that - though the country's president, Mary Robinson, has privately told the Commonwealth Secretary-General that "the Irish people have a deep affinity with the things you do" - the symbolic resonance would be too much for many republicans.) But there is no doubt that, with its intimate links to all corners of the globe, the Commonwealth is well placed to play an important role on the world stage in the next century - as a forum in which to moot international initiatives, a mechanism to further democracy and human rights and as a discreet vehicle for crisis diplomacy.

In Hong Kong, the first Chinese successor to the last British governor has invited the Secretary-General, Chief Emeka Anyaoku, to the hand-over celebrations. The new chief executive hopes, apparently, that some of the informal connections with Commonwealth associations might be maintained, even though Hong Kong will never qualify for membership. The gesture has gone largely un-noticed as part of the small change of international diplomacy. But as a testament to the potency of the Commonwealth in the post-imperial world it carries its own significance.