An ignition system (10) comprises a spark plug (12) having a first end (14) defining a spark gap (16) between a first electrode (18) and a second electrode (20). A transformer (46) comprising a primary winding 44 and a secondary winding (50) also forms part of the system. The secondary winding is connected in a secondary circuit to the first electrode 18 and the secondary winding has a resistance of less than 1 kΩ and an inductance of less than 0.25 H. A drive circuit (26) is connected to the primary winding.