A man was attacked leaving Manor House station after he confronted a group of yobs who chucked rubbish at him on the Tube.
British Transport Police are now appealing for witnesses to the shocking assault at 6pm on September 2.
The victim had spoken up after having stuff thrown at him by the five teenagers.
Anyone who was at the station or who saw what happened can contact BTP on 0800 40 50 40 with reference 398 of 02/09.
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