Voelker gas mantles - poster
The pattern
This still is filed under Campaign line as series.
Define
One line that can be replayed across executions so the campaign is a family, not a one-off.
Mechanism
Repeatable frame. Each ad is a verse. The line is the chorus. Recognition compounds because the structure is stable.
Verdict
We will run more than one execution and need them to add up in memory.
Why it works
The claim is brightness and the proof is a mistake: two apparent experts are shown misreading the product as a celestial event, which lands harder than any adjective because a character makes it and not the advertiser. The joke is pinned to Halley's Comet, which everyone was looking at that year, so the poster rents a conversation that was already running. Showing both men from behind puts the viewer in the scene as the third man, so the punchline arrives without a face to argue with. The dropped aitch and GUVNOR place the speaker as a working man, which makes the line read as overheard street talk rather than a copywriter's sentence.
Steal this when
Use this when the product's advantage is a measurable excess, brighter or faster or louder, and the honest way to dramatise it is to have a character mistake it for something famous. It only works while the reference is live, so pin it to something currently in the news and expect the poster to date.