British Transport Police said that the woman killed after being hit by a train in south London was believed to be in her thirties.
Her son, who also died following the collision, is thought to have been three years old.
Senior Investigating Officer Detective Chief Inspector Iain Miller said:
Our thoughts remain with the family and friends of the woman and child involved in this tragic incident.
Officers are continuing to work to establish the full circumstances surrounding the incident, although early indications show that no one else was believed to have been involved.
More top news
The painting, entitled 'Beautiful Beautiful George Michael Love Painting', was auctioned to help raise funds for HIV and Aids prevention.
The 38-year-old victim was standing on a busy Victoria Line train when another passenger approached him.
The boy, called Roman, told police call handler his mum "is dead" and "she's closing her eyes and not breathing".