Its people reduced to eating leaves and berries, its children dying of cholera, farms choked with weeds and industry at a standstill, Zimbabwe has plunged ever deeper into misery and penury. At each stage, things seemed as though they could not get worse.

Each month, however, the cruelties inflicted by a repressive regime have intensified. Robert Mugabe, an 84-year old dictator, has showed himself indifferent to suffering and impervious to pressure. And now he parades his megalomania as a taunt to the outside world. Zimbabwe, he declared last week, was “mine”. No one could take the country from him.

The world has watched the slide towards starvation and collapse in despair. At each stage, Britain, the former colonial ruler has muffled its reaction. Diplomats appeared to think that quiet diplomacy in tandem with Zimbabwe's neighbours would achieve more than an open call for Mr Mugabe's overthrow, which, the Foreign Office believed, would be used by the President as proof that colonialists were plotting against him.

Mr Mugabe has made a mockery of African neighbours who urged him to negotiate with his opponents. He has danced rings around the so-called international community. He has outwitted the political Opposition, scorned the result of an election and killed his defenceless compatriots. He is now convinced that he is untouchable, that he cannot be removed from power either by his opponents in Zimbabwe or by any external force.

So far, he has been proved right. Harsh words at international meetings have had no effect. Isolation makes no difference to a country where money no longer has value and government no longer functions. It is high time David Miliband recognised that international intervention is the only course now available to save more than seven million people from catastrophe. Britain's reticence has been not only fatuous; it has encouraged Mr Mugabe in his hubris and the pampered party and military elite to believe they can hang on and outlast their enemies.

Britain is guilty of more than feeble diplomacy. It has failed to ensure all the loopholes are closed in this country. The United States Treasury has named some 21 companies that it has placed on its blacklist that are still trading with Zimbabwe. Disgracefully, many of these are in Britain or in terrorities controlled by Britain (see page 6).

What makes the failure to deal with these companies particularly lamentable is that targeting Mr Mugabe's entourage and the companies that may make their life easier is supposed to be a major part of the British Government's strategy for dealing with the regime. If even this policy is not pursued with sufficient vigour then what is left?

Any talk of wanting to keep open a lifeline to the people of Zimbabwe is hypocritical. The people have long lost hopes of food and support from abroad. The only lifeline is to the regime now in power.

Gordon Brown has declared that “enough is enough”. He is absolutely right. But words do little to halt cholera or feed children dying of starvation. They do little to rattle a regime that is so far steeped in evil that it dare not now retreat. It is high time Britain called for an emergency meeting of the UN Security Council to authorise armed intervention.

There are enough legal powers, including the visible threat Zimbabwe's collapse now poses to the health and security of its neighbours. Mr Miliband should respond to Mr Mugabe's odious claim with his own démarche. The world can take his despairing country from him. And it must.