A pensioner was assaulted by a group of teenagers as he left a train at St Pancras International Station.
The 72-year-old man had confronted the boys who were throwing sweets at other passengers before they attacked him at just after 10.30am on December 19.
One of the group, aged around 16, punched him in the face and he was again punched and kicked as he left the First Capital Connect train at platform A.
The elderly man was taken to University College Hospital, bleeding from his face.
Police released a 15-year-old who was arrested at the scene and have published CCTV images of three other suspects online.
Sergeant Mike Boyce said: “This was an unprovoked and malicious attack, and the level of assault is shocking.”
Anyone with information is asked to contact British Transport Police on 0800 40 50 40 or text 61016 quoting LNA/B2 of 20/12/13.
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