The George Stephenson-built Killingworth Billy was believed to have been constructed in 1826.The locomotive, in common with the two older survivors, came into being to move coal, an engineering proposition that has midwived Mallet Compounds and seven coupled axles and electric motors that look like mis-shapen bricks and all sorts of diesel technology to keep four main tracks fluid.
However, a new investigation of the engine, on show at North Shields Stephenson Railway Museum, suggests it was constructed in 1816.
That would make it the third-oldest surviving locomotive in the world.
It would also be the oldest surviving locomotive built by Mr Stephenson and the oldest surviving with a standard gauge.
TWO CENTURIES OF STEAM POWER.
George Stephenson's Killingworth Billy appears to have pre-dated his Rocket.