When David Cameron announced in his Big Society speech last spring that he intended to create a "neighbourhood army" of 5,000 full-time, professional community organisers, most people probably imagined that he was talking about mobilising the kind of worthy folk who habitually volunteer for good deeds.

He spoke glowingly of training such organisers with the skills needed to identify local community leaders, help people start their own neighbourhood groups and assist communities to tackle their problems.

What could possibly be wrong with that? Well, to those with tuned-in antennae the word "army" was one clue that something was very wrong with it. For what Cameron almost certainly didn't realise was that the inspirational leader he credited with creating the concept of the community organiser, Saul Alinsky, was a man who did believe in the creation of an army — a revolutionary army, no less, to overthrow Western society. And the community organiser was its designated recruiting-sergeant. 

It's a fair bet that hardly anyone in Britain has heard of Alinsky, a radical Marxist Chicago activist who died in 1972. A master of infiltration, Alinsky wooed Chicago mobsters and Wall Street financiers alike. Successive Democratic politicians fell under his spell — including one Barack Obama, who worked as an Alinskyite community organiser before entering politics. 

Mesmerised by Obama's stunning political trajectory and hoping that some of the glitter of America's First Community Organiser would settle upon the Big Society idea, Cameron was only too keen to extol Alinsky as his own inspiration. 

Astonishing as this may seem, Britain's new Conservative Prime Minister thus effectively declared himself a follower of a left-wing radical who set out to undermine Western society through subterfuge. 

For Alinsky was a "transformational Marxist" in the mould of Antonio Gramsci. He promoted the strategy of a "long march through the institutions" by capturing the culture and turning it inside out as the most effective means of starting the revolution. 

His creed was set out in Rules for Radicals, which he dedicated to Lucifer, whom he called the "first radical". For Alinsky, "change" was his mantra. Sound familiar? It was the slogan repeated incessantly by both Cameron and Obama. But what Alinsky meant was a Marxist revolution achieved by slow, incremental, Machiavellian means. 

This had to be done through systematic deception, winning the trust of the naively idealistic middle-class by using the language of morality to conceal an agenda designed to destroy it. And the way to do this, he said, was through "people's organisations" set up by community organisers.