A young woman with a toddler on her knee was filmed by a fellow passenger on the Croydon to Wimbledon tram service shouting racist abuse.
The dark-haired woman launched her foul-mouth rant in front of her tiny blonde-haired child, despite pleas from other passengers to stop.
Yesterday, the video of her vile tirade had attracted more than 125,000 views on YouTube.
British Transport Police said last night that a 34-year-old woman from New Addington had been arrested.
Warning: The video contains graphic content.
What hope for the poor child?