L-plate
From Longman Dictionary of Contemporary EnglishRelated topics: Motor vehiclesL-plateL-plate /ˈel pleɪt/ noun [countable] TTCa flat white square with a red letter L on it, that must be attached to the car of someone who is learning to drive in Britain → P-plateExamples from the CorpusL-plate• Residents say too many learner drivers are taking lessons in their streets, and now they want the L-plates moved on.