A person to whom this subsection applies shall be guilty of an offence if, in licensed premises, he knowingly allows any person to sell intoxicating liquor to a person under eighteen.

Subsection (1) of this section applies to a person who works in the licensed premises in a capacity, whether paid or unpaid, which gives him authority to prevent the sale.

Subsection (1) of this section has effect subject to section 169D of this Act.