What are the defences for a mischief charge?

What are the defences for a mischief charge?

No person commits mischief within the meaning of this section by reason only that:

• he stops work as a result of the failure of his employer and himself to agree on any matter relating to his employment;
• he stops work as a result of the failure of his employer and a bargaining agent acting on his behalf to agree on any matter relating to his employment; or
• he stops work as a result of his taking part in a combination of workmen or employees for their own reasonable protection as workmen or employees.
• he attends at or near or approaches a dwelling-house or place for the purpose only of obtaining or communicating information.