The British Nobility: Rooted

"'I wonder if it wouldn't have been better if the Almighty had created us all as - well - as sort of plants. You know, firmly embedded in the soil. Then none of this rot about wars and boundaries would have come up in the first place.'
The young gentleman seemed to find this an amusing thought. He gave a laugh, then on further thought laughed some more. I joined him in his laughter. Then he nudged me and said: 'Can you imagine it, Stevens?' and laughed again.
 'Yes, sir, ' I said, laughing also, 'it would have been a most curious alternative.'
'But we could still have chaps like you taking messages back and forth,  bringing tea, that sort of thing. Otherwise how would we ever get anything done? Can you imagine it, Stevens? All of us rooted in the soil? Just imagine it!'" (108)

Ishiguro utilizes the dialogue between Mr. Stevens and Mr. Cardinal to ironically convey a gap between reality and the British nobility of the time.  The symbolism of people, specifically noblemen, as "plants" addresses their being "rooted" and their concerns with war as "rot". This is ironic in that it is expressed by a nobleman himself. The gap is illustrated by describing the noblemen as rooted in their ways and their efforts in world affairs such as war as being rot, or a wasted effort. In the novel, Mr. Cardinal muses over the idea of such a thing yet the similarities between his imagined scene and that in which he is actually placed are obvious. Thus Ishiguro uses the choice of speaker well here for the irony would not be present if this idea were brought up by any other, even the narrator Mr. Stevens.
Furthermore, that which is alluded to by Mr. Cardinal's "most curious alternative" is central to the theme of the novel for its direct correlation to the ending of the era in which noblemen decided the fates of the world. Ishiguro introduces the struggle underwent by noblemen to accept that theirs was no longer the predominant role in world politics through his ironic display of the out-dated nature of their work in Mr. Cardinal's allusion of people to trees.