A sister of the Mallard steam engine is making a speed run from London's King's Cross to York to mark 75 years since the record breaking run.
It will make three trips at 90mph, the fastest for a steam engine in almost half a century, over the East Coast Main Line.
Bittern, an A4-class engine which was built in 1937 and is almost identical to the world's fastest steam loco, Mallard.
The train, which is carrying 250 passengers, has been granted special permission by authorities to exceed the 75mph limit for steam trains.
Today's run commemorates Mallard setting a record speed of 126mph near Grantham on July 3 1938 - a feat that remains unbeaten 75 years later.