My view is No.
Adjudicators love to use the words "substantial compliance", and just missing those two words is unlikely to be considered a serious error. plus you parked over a clear white line, so should have looked for a sign. However, you have the legal right to appeal the matter at London Tribunals. If you win, you pay nothing. If you lose, you pay the full PCN penalty, but that is all, there are no other costs.