On 8 September shortly before 10pm, officers were called to the line following reports of a casualty on the tracks.
Paramedics also attended however sadly a man was pronounced dead at the scene. The incident is not being treated as suspicious.
The man was identified as 81-year-old Colin Riddett.
Mr Riddett was born in Portsmouth, but lived in Hackney, London and also had a second home in Portsmouth.
Despite extensive enquiries, officers have been unable to trace Mr Riddett’s next of kin or any other family members to inform them of this sad news.
They are appealing for any relatives or anyone who may have information about Mr Riddett’s family to come forward and assist their investigation.
Anyone with information is asked to contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 866 of 08/09/21.