It's rush hour; 80 degrees in the shade, 100 degrees and more on the Tube. Your fellow travellers throng the platform a dozen deep. Your train arrives, already gorged with passengers. You end up splayed diagonally between a foul-smelling street-dweller and an insurance agent from Penge, one toe clinging to the floor, a hand clawing desperately at the strap. Then, raising your nose a moment from your neighbour's armpit, you catch sight of a small, white rectangle containing balm for the soul.
Ah, the salutary spring that is poetry! What you have found, in that most prostituted of public spaces, is something that doesn't seek to seduce you away from your cash with promised fulfilment of created needs. Rather, Beatrice-like, those few brief lines can, for a small interval at least, transport the aspirant spirit out of that stinking abode of the damned to a higher plane and to the remembrance that our nature, if half bestial, is also half divine.
For this deliverance we have to thank three writers, Gerard Benson, Judith Chernaik and Cicely Herbert, who in 1986 convinced London Underground that the traveller's environment could do with some serious enrichment. With additional funding from London Arts and the British Council, the scheme has succeeded far beyond expectations. Passengers seem to love it, judging by the success of Poems on the Underground, an anthology of the featured works, and the project has been copied in cities around the world. Even the anthology has had its imitator, with a pleasing volume of verse parodies on the theme of transport entitled Poems Not on the Underground.
Eighteen years on, Benson, Chernaik and Herbert are still involved, making up the panel that selects six poems three times a year from a shortlist of works submitted by publishers. Their choices are cosmopolitan and eclectic: at least two of every six will be by living poets; and you may find translations from just about every corner of the globe.
The almost haphazard nature of the selections complements the idea of "scattering poetry around in public places", as Chernaik puts it; part of the scheme's appeal is in not knowing where or when you might come across something new and striking. "It's wonderful that the response to the poems has been so enthusiastic," Chernaik says. "We get a lot of people contacting us who can remember a line of a poem they've read and are wondering if they can get hold of a copy." It's true that lines or images read on the Tube have a remarkable tendency to stick in the head. One of my favourites is a neat and simple three-liner called "Separation" by the American poet W S Merwin: "Your absence has gone through me/Like thread through a needle./Everything I do is stitched with its colours."
"For many people who care about literature, poetry remains a private and somewhat obscure and esoteric passion," Chernaik writes in her introduction to the anthology. "Perhaps this is one source of the popularity of our scheme, which is quiet and unobtrusive, a matter of a poem appearing here and there, at irregular intervals." One could argue that the scheme in fact militates against the idea of poetry as a private pursuit; that it inevitably gives priority to a certain kind of lyric poem - brief, instantly apprehendable, with little complexity or ambiguity. Or, worse, that it promotes poetry as a kind of dishcloth wisdom that aims at no higher response in the reader than a wistful "hm" of assent.
But that would be churlish. While you're unlikely to encounter work by such uncompromising hard nuts as, say, Jeremy Prynne or Geoffrey Hill, there's no doubt that Poems on the Underground has turned countless people on to poetry who would otherwise never have given it a thought - and the whole thing is not for profit. That, surely, is worth celebrating next time you venture into the ninth circle of hell at rush hour.
New Poems on the Underground, edited by Gerard Benson, Judith Chernaik and Cicely Herbert, will be published by Cassell in the autumn (£6.99)