"Soldiering now is much less about physics and much more about philosophy and social anthropology,"

Carleton-Smith expanded. "It's all about people, cultural empathy and emotional intelligence. The issues here are based around blood and soil, not institutions."

Indicative of just how little the concept was understood outside Afghanistan was the reaction to Carleton-Smith's remarks in an interview that appeared in the Sunday Times in October, in which he made the rational observation that the war was "unwinnable" in purely military terms.

Within hours of publication, amid an international furore, his comments had been reinterpreted to suggest that the Taliban were "unbeatable" - a very different conclusion to the one he had suggested.

Yet, even within the British army the embrace of the concept remains partial and flawed at base level. British units remain under-manned and ill-resourced beside the scale of the geography and complexity of the insurgency in Helmand, ensuring that they remain over-reliant on the use of force to defend themselves and project their influence.

It is ironic that as their last units left Helmand for a second time, 16 Air Assault's most recent tour would probably be best remembered for the audacious and complex transfer of 220 tonnes of turbine machinery through 75 miles of Taliban territory to the power plant in Kajaki, without the loss of a single man.

Despite its brilliant execution, the operation was a conventional, if hugely complicated, manoeuvre more akin to armoured operations in the desert during the Second World War than today's war among the people. It was an "absolute" act, rooted in the need to safeguard US development funds that may ultimately have less impact on the campaign than the more subliminal influences Carleton-Smith sought to exert on Helmand's mood.

"We live in a world where too many believe in science and not enough in art," he told me a few weeks before the operation. "There is a hunger for absolutes and that is not the domain of the operational commander. Tangible empirical metrics, for which there is an insatiable appetite, undermine the key metrics for progress."