UPDATE: A rep for Heathrow provided the following statement to Consumerist:
“Heathrow Terminal 5’s signage and passenger wayfinding has not changed. Samsung have rented advertising space in Terminal 5 with a tongue-in-cheek campaign using the line: ‘Terminal Samsung Galaxy 5S.'” [More]
heathrow airport

Heathrow Airport’s Terminal 5 Turning Into Giant Two-Week Ad For Samsung
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5.16.14