In order to be trespass to land, Ziwei’s acts need to be direct and intentional or negligent interferences with land in the possession of another. In order to be direct, there must be no significant volition which intervenes between what Ziwei does and the interference. When Ziwei pulls down the old walls and bricks fall onto Dahlia’s property, there is a direct trespass. The actions of the wind in blowing a cup onto Dahlia’s property would also have been direct enough and negligently brought about: Gregory v Piper. Given that Ziwei could have taken into account the actions of the wind, the blowing of the cup onto Dahlia’s land would have been expected. Naturally Ziwei commits trespass to land when he retrieves the aforementioned items without seeking permission to do so. (But this is subject to the defence of recapture, discussed in chapter 13.) Dahlia’s drone obviously was not being flown at any great height and its entanglement in Ziwei’s trees is evidence of trespass to his land. However, Dahlia was no longer in control of the drone after it got entangled. In this way, when the drone falls onto Jo-Beth’s land this is an indirect interference (brought about presumably by the actions of the wind shaking the tree) and does not permit an action in trespass. Although Blast Gases plc would have an implied licence to enter land for the purpose of checking the gas meter (see Chapter 13 on Defences), the simple making of a mistake about whose property he has entered is no defence and indicates a trespass to land.