Thank you for that: the mention of Panmure was the missing clue. It looks as if the text was published in Helena Mennie Shire's small book Poems from Panmure House (Sebastian Carter: Cambridge, 1960). Copies are pretty scarce, though: the nearest to me is probably the one at Manchester University. I'll have to see if I can get a look at it.

Since the thread is back again, I'll just add that Hester and I subsequently made up our disagreement!