(1) An occupier of premises owes a duty of care ("the common duty of care") towards a visitor thereto except in so far as the occupier extends, restricts, modifies or excludes that duty in accordance with section 5.

(1A) Without prejudice to the generality of subsection (2), in determining the extent of the common duty of care of an occupier towards a visitor, and whether it has been complied with by the occupier, regard shall be had, as appropriate, to all of the circumstances and matters referred to in that subsection, which shall include but are not limited to the following:

(a) the probability of a danger existing on the premises;

(b) the probability of the occurrence of an injury to, or of damage suffered by, a visitor by reason of a danger existing on the premises;