Under section 11 of the Public Order Act 1986, there is a requirement to give the police notice of a march if it is intended to: (1) demonstrate support for or opposition to the views of any group; (2) publicise a cause or campaign; or (3) mark or commemorate an event. The purpose of the proposed march by Alice and the residents is to publicise their opposition to the building of a new toxic waste landfill site, which falls under publicising a cause or campaign. Therefore, they are required to inform the police of their intention to hold the march. Notice is not required if the march is purely spontaneous or for a funeral procession. 

Key Point: The Public Order Act 1986 mandates that notice be given to the police for public processions intended to support or oppose views, publicise causes, or commemorate events. This requirement helps ensure public safety and order during such events.