A client, Dennis, a developer, has recently purchased two vacant blocks of land beside each other in a newly subdivided area. He commences building two townhouses for investment purposes. There is a vacant block beside the blocks he is developing and to make it easier to work on his own sites, equipment and materials are stored on that site. Sometimes it is also used as a car park by his workers. Dennis has now received a letter from the owner of the vacant block threatening legal action against him.

Explain to Dennis the likely nature of the legal action, why he may be liable and the possible consequences.