What is the current state of the law on liability for trespassing on private premises?

The leading case on the subject is Indermaur v. Dames (1866) L.R. 1 C.P. 274, 35 L.J.C.P. 184, L.R. 2 C.P. 311, 36 L.J.C.P. 181. In that case the occupier of a factory was held liable to the plaintiff, who was the servant of a gas fitter employed by the defendant, and who while testing the gas fittings of the defendants’ premises fell through an unenclosed space in one of the upper floors. It was contended that such a visitor enters at his own risk, and must take the premises as he finds them. This contention, however, was rejected, and Willes, J. [35 L.J.C.P.] gave a statement of the law which has, without exception, been applied since that time: It was also argued that the plaintiff was at best in the position of a bare licensee or guest, who, it was urged, is only entitled to use property as he finds it, and whose complaint may be said to wear the colour of ingratitude so long as there is no design to injure him * * * We think this argument fails, because the capacity in which the plaintiff was there was that of a person on lawful business, in the course of fulfilling a contract in which both the plaintiff and defendant had an interest, and not upon bare permission * * * The authorities respecting guests and other bare licensecs, and those respecting servants and others who consent to incur a risk, being therefore inapplicable, we are to consider what is the law as to the duty of the occupier of a building with reference to persons resorting thereto in the course of business upon his invitation, express or implied * * * And with respect to such a visitor, at least, we consider it settled law that he, using reasonable care on his own part and for his own safety, is entitled to expect that the occupier shall on his part use reasonable care to prevent damage from unusual danger, which he knows or ought to know; and that, where there is evidence of neglect, the question whether such reasonable care has been taken by notice, lighting, guarding or otherwise, and whether there was contributory negligence in the sufferer, must be determined by the jury as a matter of fact.