Police want to identify the man pictured above
The teenager was assaulted twice on a service at around 6.30pm on Wednesday, 28 August.
The man then followed the victim off the train at Leyton and tried to engage him in sexual conversation.
Officers from British Transport Police believe the man photographed may have information which could help their investigation.
If you recognise him, or witnessed what happened, you can contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 640 of 28/08/19.
Alternatively you can call Crimestoppers anonymously on 0800 555 111.
