This is a neat idea for an advertisement. Kit Kat's slogan is break me off a piece of that kit kat bar. The bench are actual kit kat pieces and the wrapper signifies the breaking. They took something very ordinary and use it to create something great.
The call to action and the hook for this PSA is "To many people eat on the streets." What is really interesting about this PSA is that the storm drain is acting as a dishwasher for the plates. The target audience of this PSA could range from adolescent children to the elderly. I feel that the whole point of this PSA is to bring awareness to Poverty.
The Tate Gallery By Tube; by David Booth of the agency Fine White Line, 1986. ‘The Tate Gallery By Tube’ poster was commissioned for Art on the Underground, a poster-commissioning initiative launched in 1986. | Forgotten London Underground posters - Telegraph