Michael Semple and Mervyn Patterson, who have just been expelled from Afghanistan, were two of the best political officers in the country. It would seem that they have been expelled for precisely what made them uniquely useful to Afghanistan and the international community: their courage, relationships, energy and skills, which took them to the most remote and dangerous areas.

I first met Semple at the beginning of 2002. The Taliban government had fallen a few weeks earlier, it was midwinter and I was in Chaghcharan, a town cut off by snow. A crowd of 100 watched a Hercules plane land and Semple emerge - a tall, broad-shouldered figure with a great shaggy light-coloured beard, dressed in local shalwar kameez. He proceeded to give a compelling speech about the new government in rapid, fluent, colloquial Dari with only a hint of an Irish accent.

As I continued through the villages of the Sar Jangal valley, inaccessible by car, I found that almost every family knew and admired Semple. Later I carried greetings from villagers to him in Kabul, where he sat on his office floor, with a Thermos of tea and trays of nuts and raisins, receiving a succession of guerrilla commanders, farmers and new officials, teasing them about village politics and reminiscing about old adventures.

He was then one of a group of highly experienced men, including Germans, a Dutchman, a Swede and a South African, employed by the United Nations to shape the new Afghan state. Over the following months he and most of his colleagues were replaced with less experienced foreigners, whose knowledge was less threatening. Yet since Semple and the others loved Afghanistan they found work as junior diplomats or in charities so that they could remain on the ground, and gradually everyone, from ambassadors to generals, began to court them again.

By 2007 Semple had been working in Afghanistan for more than 20 years: through the Russian occupation, the civil war and the Taliban period. He had studied Afghan history and anthropology, visited all the remote provinces, often on foot or horseback, and knew thousands of Afghans. He was reappointed to a senior position in the European Union office and Patterson was a senior political officer in the United Nations mission. My last memory of these two Irishmen, one from the north and one from the south, is of them tumbling, dusty, out of the backs of jeeps at dusk and entering the mud streets of the old city, having just retraced the British retreat of 1842, and repeating the troubling, surprising and very funny conversations that they had held along the route.

Their skills, and those of about half a dozen others, were the reason the political sections of the EU and the UN Afghan mission were the envy of all the embassies in the country.

Just before Christmas they went to the town of Musa Qala in Helmand - a province that alone produces more than 50% of Europe’s heroin. It is the base for 7,000 British troops and the centre of some of the fiercest fighting. Musa Qala had been in the hands of the Taliban for most of the previous year and had just been retaken by foreign troops. Little was known about it. Journalists had been kidnapped in the area, soldiers had been killed and the road to Kandahar was so dangerous that even Afghans were reluctant to travel on it.

The majority of the foreigners there could not speak any Afghan language and had little sympathy for Afghan traditional culture. They were imprisoned in a security cage that prevented them from spending a night in an Afghan house. The soldiers in Helmand were only on six-month tours; British diplomats could visit only on short day trips in armoured vehicles with large bodyguard teams.

The visit of Semple and Patterson was, therefore, uniquely valuable. Here were two experts with the language, the cultural understanding and decades of intense experience who were able to try to make much-needed sense of this fractured, criminalised, semi-tribal, insurgent-haunted town. Such knowledge is vital not just for the international community but also for the Afghan government itself.

Yet the Afghan government responded to their trip by declaring each of them “persona non grata”, by removing their diplomatic immunity and expelling them from the country.

Diplomats are commonly expelled by hostile, paranoid regimes. British diplomats have been expelled from Russia for spying; from Uzbekistan for reporting on human-rights abuses and, longer ago, from Sri Lanka for reporting on fraud in a general election.

Afghanistan, however, is not supposed to be a semi-hostile, illiberal or totalitarian nation. It is supposed to be a constitutional state with an elected parliament, financed with billions of dollars of international aid and supported by more than 40,000 foreign troops. There is supposed to be no difference between the Afghan government and its western allies.

Why, then, would the Afghan government insult its closest and most powerful partners by expelling their senior diplomats? Why does the Afghan government not want highly informed foreigners to meet locals in Musa Qala?

The unprecedented western investment in Afghanistan assumes that the Afghan government is serious about eliminating drugs and defeating the Taliban. Did Semple and Patterson discover something different? Or is the Kabul government simply fed up with foreigners who micromanage and second-guess their decisions?

Whatever the reason, both Afghanistan and the international community lose by this expulsion.

International policy in Afghanistan has long been surreally distanced from reality. Britain and its allies continue to throw immense numbers of troops and dollars in pursuit of grand fantasies. Their analysis too often mingles management jargon, misapplied analogy, moralistic rhetoric, impatience and fear. They have failed in their ambitions to eliminate poppy growing and opium production, to deliver development to insurgency areas and to defeat the Taliban. They are paralysed and are in danger of lurching from troop increases to withdrawal, from engagement to isolation. They need a modest and sustainable strategy which recognises that in Afghanistan all politics is local.

Semple and Patterson know more than any other foreigner what Afghanistan is and what it is capable of, what it should and should not fear, what it can reasonably hope to achieve and what, on the other hand, does not matter. They have worked through decades of horror without losing their faith in Afghans or their sense of humour. Their practical knowledge is the only way of avoiding slick and dangerous decisions and supporting the slow process by which Afghanistan will become a more humane, prosperous and stable state.

There is no shortage in Kabul of charmers with flattering analyses and tickets home. But there are few such genuine and constant friends of Afghanistan. Everyone will benefit from their return.

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