'By Paying Us Your Pennies' - The Wonderground Map of London Town
The pattern
This still is filed under Data as proof.
Define
A chart, map, or count that is the argument, not an illustration next to the argument.
Mechanism
Sighted evidence. The reader is asked to believe their eyes: a bar, a share, a spread on a map.
Verdict
The claim is comparative or quantitative and the figure can be read without a caption doing the sell.
Why it works
The map is deliberately too dense to read at a glance, which is the point: it is aimed at people who are stuck for four minutes and have nothing to look at. Reward for reading is built in at two scales, the big shapes work from across the platform and the jokes only pay out at arm's length, so the same poster keeps working on the hundredth wait. The border sentence states the benefit in plain second person, we take your pennies and in exchange the city opens up, which converts a fare into a purchase. Borrowing the borough coats of arms gives a commercial poster the manners of a civic document, so the jokes land as charm rather than as noise.
Steal this when
Use this when your audience is captive and bored, a waiting room, a queue, a lift lobby, and the metric you actually want is dwell time rather than an immediate action. Build in two reading distances so the piece rewards the second and tenth look, not just the first.