BBC
We've just received an update from British Transport Police.
They say a 32-year-old man arrested yesterday is now being treated "as the only suspect".
"A 35-year-old man from London who was also arrested at the scene has been released with no further action," the update reads.
"It was reported in good faith to officers responding to the incident that he was involved in the attack, and following enquiries we can confirm that he was not involved."