An act done by a person in contemplation or furtherance of a trade dispute is not actionable in tort on the ground only—
An agreement or combination by two or more persons to do or procure the doing of an act in contemplation or furtherance of a trade dispute is not actionable in tort if the act is one which if done without any such agreement or combination would not be actionable in tort.
Nothing in subsections (1) and (2) prevents an act done in the course of picketing from being actionable in tort unless it is done in the course of attendance declared lawful by section 220 (peaceful picketing).
Subsections (1) and (2) have effect subject to—
and in those sections "not protected" means excluded from the protection afforded by this section or, where the expression is used with reference to a particular person, excluded from that protection as respects that person.