20.—(1) Any person who—
(a)trespasses on any part of the railways; or
(b)trespasses on any land of the undertaker in dangerous proximity to the railways or to any apparatus used for or in connection with the operation of the railways,
shall be guilty of an offence and liable on summary conviction to a fine not exceeding level 3 on the standard scale.
(2) No person shall be convicted of an offence under this article unless it is shown that a notice warning the public not to trespass on the railways was clearly exhibited and maintained at the station on the railways nearest the place where the offence is alleged to have been committed.