Final answer:
The statement is false; under the Trespass to Property Act, an owner or occupier's consent is required for a person to remain on the property, and they can ask someone to leave without providing a valid reason.
Step-by-step explanation:
The statement \"A person is not trespassing under the Trespass to Property Act if the owner or occupier cannot give a valid reason why they should leave\" is False. The Trespass to Property Act typically grants owners and occupiers the right to decide who can and cannot be present on their property. Therefore, a person can indeed be trespassing if they remain on property without the rightful owner or occupier's consent, irrespective of whether a valid reason is provided or not. It is the prerogative of the owner to control access to their property, and a failure to heed a request to leave can constitute trespassing.