Metalinguistic comments that is, as in the novels of Kingsley Amis, Len Deighton and Ian McEwan. Reading A Most Wanted Man (2008), I came across several references to accent but also one to who/whom:
But for how long? And from who? Whom? (p. 275)
The speaker is the elderly Scottish banker Tommy Brue, one of the main characters in this novel situated in Hamburg.
Read more about all this, though not about John Le Carré, in chapter 7 of my forthcoming book Describing Prescriptivism.