L'Artisan Moderne (André Marty decorating firm) - poster
The pattern
This still is filed under Demonstration ad.
Define
The product does the arguing. The viewer sees the thing work, not a slogan about the thing working.
Mechanism
Proof by performance. The claim is the action: a visible, testable result the reader can replay.
Verdict
We can show a result in seconds
Why it works
The poster sells a service by dramatising the moment of delivery rather than showing the goods, which sidesteps the impossible problem of depicting furniture, objets and complete schemes in one image. The joke - a tradesman standing in a lady's bedroom, both unbothered - buys attention and simultaneously communicates the proposition, that this firm works in your home. Line-only drawing over flat colour keeps the scene readable at poster distance, and the address block is bottom-loaded with the numbers weighted heavier than the street names because the number is what a reader has to retain.
Steal this when
You sell a service whose product cannot be photographed - installation, consulting, fitting, repair, in-home anything - and the clearest thing to show is the moment your person arrives. Use the weighted-number address block whenever a piece must carry many locations and the reader only needs to hold one.