A class of streamlined 4-6-2 Pacific steam locomotives built for the London and North Eastern Railway. Designed with an aerodynamic casing to reduce air resistance at high speeds, they represent the peak of British steam performance. The class includes Mallard, the locomotive that holds the world speed record for steam traction.
Heard on the job
You can tell an A4 from a mile away by that wedge-shaped front end and the chime whistle.