The signs or lines were not clear (or visible) at the time I was issued the PCN, am I still liable to pay?

When challenging or appealing a PCN, you should provide any evidence, such as photographs, relating to the signs or lines you think were not clear and/or provide an explanation as to why.

Signs and lines serve to advise the motorist of a restriction and must not mislead. Trifling omissions, however, do not render a sign or line unenforceable. So long as the sign or marking does not mislead and remains substantially compliant with the requirements of the regulations, the restriction is enforceable.

See Key Case: R (on the application of Herron and Parking Appeals Limited) v The Parking Adjudicator and others (2010) and Letts v London Borough of Lambeth PATAS 1980151656 (1980).