You can buy Double Bill here or here. And here's the poem:
Ichigoro Yuchida, keen to improve
his colloquial English, puzzles over
a text with his (equally baffled) teacher.
They can't seem to find dolly old eek
in the phrasebook. And why, during a shipwreck,
should Mr Horne laugh when our heroes
drag themselves up on deck? So many queries…
in the end, they think best to seek wisdom
from the writer, which is how they come,
courtesy of Mr Took, to knowledge
of some comic stereotypes, a secret language,
a national habit of wryness, a way of talking
as if one could make a joke of anything,
of code, of hiding from the law, of love.