A woman is wanted after a teenager was sexually assaulted on a train to Milton Keynes.
The teenage girl reported the incident on Monday August 19 after a women repeatedly touched her on the thigh while travelling from London Euston.
The woman then left the train at Milton Keynes.
British Transport Police have released a CCTV image of a woman who may have more information regarding the incident.
Anyone who knows her is asked to contact BTP by texting 61016 or by calling 0800 40 50 40 and quoting reference number 1900071882.