www.Austin7Ulster.com › Champion D21 18mm Spark Plug Champion D21 18mm Spark Plug £4.99 D21 - 18mm spark plug for Low Compression Heads etc D21 - 18mm spark plug for Low Compression Heads etc Add To Cart Added! You Might Also Like HT Ignition Lead / Cable £1.65 12v Indicator Bulb £1.99 12V 150mA MES 10mm Bulb (fits switch panel) £0.75 Champion D16 18mm Spark Plug Copper Core £4.96 Original Lucas NOS 2 way junction box £17.50