The C2C train I was on this morning slowed then stopped outside Elm Park station. After a while the driver announced that there was a young lady walking on the track and he'd tried to get her to get into the cab but she wouldn't, so we would be delayed to make sure she was safe. Tubes were also stopped and presumably the current turned off. We moved forward at walking pace and eventually two men (passengers?) who appeared to have walked from Elm Park platform caught up with her and restrained her. She was clearly distressed and a potential tragic outcome had been avoided. We often hear of delays due to trespass but it is rare for passengers to see what is happening and the efforts made to keep the person safe.