My students have been having a spot of bother with poetry, and it’s nothing to do with the usual difficulties sixth-formers have always had with poetry appreciation, such as writing sensibly and sensitively about structure, form and the use of language, because my class does that very well.

No, it is to do with the distance between today’s readers and the world the poet inhabited. I’m not talking about the distance between, say, Milton and the modern student, though I do believe it’s a brave soul who takes on Paradise Lost with a sixth form today. Nor even the distance between romantic poets and the 21st-century teenager: “This ‘La Belle Dame Sans Merci’ - it’s about date rape drugs, isn’t it?”

What has surprised me about preparing an upper-sixth class for the unseen poetry criticism paper is the difficulty the pupils have with things which I thought were obvious, and which suddenly are not. Things that were obvious to me when I was their age but which leave them mystified.

One of the poems we looked at recently was “New England” by Sarah Wardle.

She describes a typical tourist trip to New England made very special by her visit to the grave of Robert Frost. Every English teacher would do the same if they could.

But the upper sixth? Robert Frost? Who he?

When I had recovered, I consoled them with the assurance that if such a poem were used in the exam, it would have a footnote. I hope.

I then felt compelled to offer the class Frost’s “Birches”. You know the bit about bent birch trees, leaves trailing on the floor, resembling girls on their hands and knees who have thrown their hair before them over their heads to dry in the sun?

This was completely lost upon my modern young women, for whom a world without hair dryers is unimaginable.

My biggest problem came with Philip Larkin’s “Mr Bleaney”. Perhaps you have you read it. A wonderfully bleak poem for readers in middle age, contemplating the “hired box” of a rented room which Mr Bleaney inhabited before the poet, and reflecting upon how you would feel if such “digs” (what an old fashioned word!) were all you had to show for your life. Mr Bleaney, Larkin tells us, “kept on plugging at the four aways”. The what? “It was like the lottery,” I flounder, remembering my own father’s interest in the pools - “The what?” - and his pursuit of the eight elusive draws.

For my class, all this is territory so alien that I might as well have been talking about jousting tournaments.

I keep finding that the strangest things are missing from their consciousness of the world. A Carol Duffy poem, “The Dummy”, giving vicious voice to a ventriloquist’s dummy, is only recognisable because the class has seen Chicago, with the marvellous scene in which Renee Zellweger pretends to be a dummy on Richard Gere’s lap and he - her lawyer - puts words in her mouth for the trial. “Oh!” cry my pupils, “we get it!”

What they don’t have is any sense of the music hall acts which peopled my adolescent Saturday evenings in endless TV variety shows where the ventriloquist’s dummy was forced back into his box, protesting all the way; we thought that was so clever.

“You did?” Much merriment.

If ever I wanted proof that the world has moved on without my noticing, here it is. I must be close to purple hat country. (“Purple what?”) Meanwhile, with my eye on those all-important grades, I can only hope the examiners are better tuned to the world view of today’s young readers than I appear to be. Let every poem come festooned like a Christmas tree with footnotes for things which I think are common knowledge, because do you know what? They aren’t.

Hilary Moriarty is headmistress of Bedgebury school in Kent, but writes here in a personal capacity