The speaker is riding public transport and noticing things, then immediately second-guessing the noticing. A pigeon flying up a down escalator is the kind of image a poet would love, and the speaker catches themselves: it's "too conveniently poetic." The crowds moving through the underground get the same treatment, dismissed as "too operatic." Each time, the speaker tells themselves to "qualify that," like an editor marking up a draft of their own experience.
The last stanza shifts the tone. A companion says their stop is coming soon, and the speaker answers with the same dry doubt, calling it "optimistic." But now the request flips to "quantify that," asking for something concrete, like a time or a number. The mood is wry, self-aware and a little weary. The poem seems to joke about how hard it is to simply see something without turning it into literature, while also hinting at a plain wish for a real answer.