What is the standard of care an occupier is expected to exercise in relation to an invitee?

The standard of care that an occupier is expected to exercise in relation to an invitee was set out in Indermaur v. Dames, [1861-73] All E.R. Rep. 15 as the duty to use reasonable care to prevent damage from an unusual danger which he knows or ought to know exists. That is an invitor's duty extends to both unusual dangers known to the invitor and those of which the invitor ought to be aware; the invitor must stay acquainted with the state of the property. The invitor's duty is not to prevent unusual dangers but rather to use reasonable care to prevent damages to the invitee from such dangers. What acts will constitute reasonable care on the part of the invitor is a question of fact, depending on the particular circumstances of each case.