Police are looking for a man who challenged a bag thief on a train to come forward.
The victim fell asleep on a train from Sheffield when a man took his bag from next to him.
When challenged, the thief became abusive.
A passenger on board the train - the 6.52am service from Sheffield to Plymouth on June 24 - texted British Transport Police on its 61016 number and officers met the service at Derby, escorted the man off the train and arrested him.
PC Joshua Dunn, investigating for BTP said: “Unfortunately the arresting officers were unable to obtain the victim’s details at the time so I would like to appeal for him to come forward.”
Anyone with information is asked to call 0800 405040 quoting reference MSUB/B2 of July 10 2015.