A person commits the offence of aggravated trespass if he trespasses on land in the open air and, in relation to any lawful activity which persons are engaging in or are about to engage in on that or adjoining land in the open air, does there anything which is intended by him to have the effect -

(a) of intimidating those persons or any of them so as to deter them or any of them from engaging in that activity,
(b) of obstructing that activity, or
(c) of disrupting that activity.

Imprisonment for a term not exceeding three months or a fine not exceeding level 4 on the standard scale, or both