I vaguely remember that Allingham poem (haven't read Little, Big) but it was decades ago and no way would I have got that reference.

This kind of thing leaves you vaguely paranoid that just about any book might be up to tricks you're not getting.

I haven't read Nabokov's Ada but saw a review of it when it came out, by the New Zealand writer Bruce Mason. He mentioned an offhand phrase that seemed to come out of nowhere, "Te Work-Basket". Mason was alerted by the "Te", which is Māori for "the". Like me he didn't know what "work-basket" was in Māori so he looked it up. "Paro no mahia". Māori has no "s" sound, so that's the closest you can get to "paronomasia" - which is ancient Greek for "pun".

I'm sure the reader's experience was greatly enhanced by that. My reaction was, bugger it.