Marshlink line officer Paul Bromley was returning from a trip to various stations on the line when an unexpected additional passenger joined the train.
The seagull hopped on board at Hastings and walked up and down the carriage before Paul was able to usher it to the vestibule and it hopped off at St Leonards Warrior Square.
The story has been reported in the local media. One social media user commented: “See It. Say It. Seagull.”
A Southern spokesperson said: “Paul from the Southeast Communities Rail Partnership is a great friend of the railway and he gives gull-den service to everyone who travels with us. If it weren’t for him, this seagull’s day would have taken a tern for the worse as it travelled (‘off-beak’) all the way to London!”