Tony Blair, the British Prime Minister and President of the European Union, will be centre stage at the G8 in Birmingham this weekend, and for once, much of what happens will actually matter.

The major economic nations will be there with enough financial and political muscle to save the world - or at least improve it - if only there is enough political will. There will be no need for these politicians to manufacture a crisis in order to come out smiling once it's been resolved, because this time, the crisis is real: the escalating threat from nuclear weapons on the Indian continent.

Third World debt, the dangers of global warming, India and Ireland will all, of course, feature heavily on the agenda, but India's excessive nuclear muscle and the question of peace in Ireland are the issues most likely to occupy the politicians.

Desperate attempts will be made to control India's nuclear testing, although there are bound to be divergent views. President Clinton will struggle to persuade the other seven powers to follow his imposition of sanctions on India. Japan and Canada have already lined up with the Americans but Britain, France and Russia remain unconvinced at the wisdom of following such a macho approach.

American law leaves little room for manoeuvre under a non-proliferation ruling which will end aid and credit to India, but there is a valid counter argument which demonstrates that the withdrawal of sanctions hits only the weakest and most vulnerable.

Nevertheless, with or without sanctions, the G8 countries will do what they can to try to contain the escalation of nuclear might in the Indian continent, and a sanctions package has not been completely ruled out. Senior politicians in the West, alarmed by recent evidence of the sophistication of India's nuclear tests, are determined to minimise the possibility of Pakistan being provoked to conduct its own tests.

On the Northern Ireland question, with less than a week to go before the referendum on the peace settlement, the G8 will give Mr Blair another platform from which to exert his power and influence in favour of the ''Yes'' campaign. It will be a delicate operation.

The Nationalists are overwhelmingly on board, President Clinton is already signed up and a higher profile for the President might undermine strenuous efforts to court the wavering Unionist vote.

President Clinton's appeal in a Northern Ireland context is his dominance of the world stage and his economic power. The British Government will hope even the most hard bitten Unionists may be wooed by the attractions of huge American investment and the general support of American might.

The issue of Third World debt in Mauritius will also be taken up by the Prime Minister. The eradication of Third World debt - which Chancellor Gordon Brown has made a political priority - is one of the telling issues which distinguishes this Government from its predecessors.

''We will be emphasising that debt relief alone will only clear away one barrier to economic growth,'' says the Prime Minister's official spokesman. "The summit offers an opportunity to get a clear commitment from the largest bilateral creditors to implement debt relief. On this issue, the international community must work together towards a common goal.''

If this international community is ever going to demonstrate that its commitment to reducing global warning is more than hot air, it will have to persuade America to cut down its contribution to the international pollution problem.

Although the US signed up to the Kyoto agreement, there are fears in the international community that the Americans are backsliding on their commitment to cut their consumption of greenhouse gases by 8% by 2012.

President Clinton's difficulty, here, is a practical one. He can sign whatever international agreements he likes, but that in itself will come to nothing if he cannot persuade American citizens to leave their cars at home. Telling the good citizens of the US to abandon their automobiles could be nothing less than political suicide.

Environment Minister Michael Meacher, who was John Prescott's side kick at the negotiations in Kyoto, has condemned the US's consumption of fuel. ''There are big political issues at stake,'' he has said. ''We need to build confidence with developing countries to demonstrate that the developed world clearly takes its Kyoto commitments seriously and is willing to pass on experience and expertise. If we move too hard and too fast we risk complete failure.''

There will be much tough talking in Birmingham. Tony Blair will be determined to match the rhetoric with actions, and the agenda is ambitious. There may be no immediate results but as Winston Churchill said: ''Jaw-jaw is better than war-war.'' These words have a special resonance today. And that is the great strength of the G8.