A while ago, I realised that one of the tricks – or is it paradoxes? – of speaking well in public is not to be afraid of your audience, to approach the whole encounter with an open hearted curiosity and excitement; to be interested in who your audience are and what might emerge in the alchemy of you-and-them.

Even so, nothing can quite prepare one – me – for that strange feeling of walking into a room full of strangers: as I did this week, to speak to three separate groups of seventeen year olds at Colchester sixth form centre about politics, high and popular: feminism: journalism and creative writing, organised by a remarkable teacher called Clarissa Ford.

What I learn, very quickly, on that cool Thursday morning, is how much I take for granted so many of my own cultural and political references, from the significant achievements of modern political leaders to the writings of certain 20th century authors to the arcs of development of the major social movements such as modern feminism. What I might call contemporary politics, these students – logically – call modern history.

Being shaken out of my (naive) assumption of broadly shared time lines is bloody scary but also bracing. As I am talking – often rather too fast, to disguise a faint panic that I am not reaching this young audience, and I must not lose them, whatever happens, nor exhaust them, which I am clearly at risk of doing with my dozen a minute observations and general manic form of delivery!! – I am watching them carefully: happy to note a sudden smile here, a nod of recognition there.

With group one and two, I give it my all and they are warm and fair minded in response. But I feel, perhaps wrongly, that only a few of my points get through: that politics is, in the first instance, about what you make of your own experience; always edit your own work ruthlessly; think about how things really are when you write about them. I urge them to read carefully, referring enthusiastically to an excellent article I have just read in that day’s paper, only to find that I have left it on on the London to Lowestoft train!

Many teenagers are shy of speaking out so I am grateful for the few who say what they think, regardless of how it sounds. Thinking about how hard it is to speak in a group, I suddenly blurt out: “If there is one skill I would urge you all to acquire, particularly the women here, it would be to learn to speak up in whatever way, to articulate your thoughts. It is a skill you will never regret having.”

But the most successful session of the morning – judged simply by a degree of stillness among the audience – is as at the end, with the biggest group. This time, I make my points – about politics, equality and its link to education – through telling a story: a story about two girls who are best friends at five, sharing certain dreams and aspirations, but who, by the time they are fourteeen, pass each other, without speaking, in the street.

I am partly telling them this story because in an earlier session, one student was adamant that anyone could make it in this society: that there are no real barriers of class or gender anymore. Whereas I believe, passionately, there are many subtle and not so subtle obstacles in modern Britain, not least the simplistic mantra of ‘reach for your dreams’ peddled by contemporary celebrity culture.

So I talk about V, a hugely bright little girl, who comes from an immigrant background. At eight, she wants to be a lawyer. By the age of eleven, and certainly by fourteen, she is struggling with all sorts of economic and educational difficulties. S., on the other hand, the dreamy child of a middle class family, is by the age of fourteen benefitting from every privilege ( and excess) granted to the children of the wealthy in the western world.

In other words, a mix of school choice, parental income and a dollop of good or bad luck in each of their lives, has not only pushed them far apart as people, full if misapprehensions about the other, but they are confirmed in their social class, with fatal consequences for them, and our society.

I am particularly fired up about this story not just because I have seen this drift-apart happen to real girls, and boys, but because that morning, in that same paper that I left on the train to make its own way to Lowestoft, I had read an interview with two authors of a new book on inequality, ‘The Spirit Level’ – Richard Wilkinson and Kate Pickett – who talked about how social and economic divisions harm all, poor and well off, in a society.

So now, two days, later, back at home, I am still thinking about the faces of all those Essex teenagers and who they are, away from class, and who they will become in ten, twenty, thirty years, and hoping that some of them will find the right voice, creative, political or merely personal, to make sense of the world they find themselves in, and to speak out against out against injustices they come across.

For my part, I have learned, it is the most subtle divisions, the kind we observe day in and day out and so often call ‘life’, that are the hardest to analyse and combat. ( So I make a note to myself: remember to say that. Next time.)