The speaker of "West London" sits in Belgrave Square, watching a tramp loitering with her baby and young daughter. They are all dressed in rags.
When some working men pass by, the tramp sends the girl to beg; the tramp's daughter is successful and brings back the money. However, they make no effort to beg from some richer people who pass by.
The speaker then realizes that the tramp will only beg from working-class people, who understand and sympathize with her plight. The rich are "aliens," possessing no empathy for her plight.
Like most of Arnold's poems, "West London" offers a criticism of society, although it is more political than many of the others. Here, Arnold condemns the world's lack of response to poverty. As the globe modernized in this century, wealth inequality became much greater. Arnold seems to believe that this separation has not only shifted social classes but in fact basic human empathy. The modernization has made some people "aliens" to others. Whatever community once existed amongst all people has been destroyed.
The title "West London" accentuates this idea. West London has always been a very wealthy area of the city, so the contrast between this scene and what is occurring in that richer area is implied. The title reminds us that poverty remains rampant despite the burgeoning wealth of neighborhoods like West London. In other words, it underscores the sense of people's separation from one another that the poem explores.
Like its counterpart "East London," this poem is a sonnet. It has fourteen lines and four stanzas, the first two with four lines each, and the second two with three lines each. In between the four-line and three-line stanzas, the poem shifts from an anecdotal account to the message that the speaker took from this experience. It is the same shift as used in "East London" - the second part delivers the moral of the story.
In addition, Arnold also employs a lot of inverted phrasing in this poem, such as "A tramp I saw" and "The rich she had let pass." Grammatically, this inversion changes the subjects of the sentences. A traditional phrasing - "I saw a tramp" - presents the speaker as the subject, and the tramp as the object. The inversion suggests that the tramp is in fact the subject, that which the reader should focus on. Overall, this structure emphasizes social class - "a tramp" and "the rich" - to underscore the overall theme. In the same way that the characters in this poem see one another in terms of social class (the tramp ignores the rich, and vice versa), so does Arnold focus on class.
Ironically, the poem has a lot of empathy, despite its critical tone. Arnold accomplishes this through his diction. Phrases like the "unknown little" express how the poor are disappearing from the eyes of the "unknowing great," or the rich. Such choices are meant to inspire a desire for change in the poem's readers, to make us wish we could all see one another as people and not as social classes. This poem remains relevant because this desire has not by any means by satiated even today.