Network Rail said there was a "slow-speed buffer collision" at around 6:20am and two people suffered minor injuries.

There is no expected service disruption as the crash was "very minor", the spokeswoman said.

Passenger Natasha Coella, 36, was on the train - having boarded at Stevenage, and said: "We just all went flying. It's as if while we were slowing down it kind of accelerated again."

She said she felt as though she had pulled her collar bone, adding she could see a few injuries, but nothing serious.

"No one expected it, and people just went from one end of the carriage to the other," she said.