Tommy Robinson, a 42-year-old far-right activist whose real name is Stephen Yaxley-Lennon, was arrested at Luton Airport after returning from Portugal.
He was wanted in connection with an alleged assault at St Pancras station on July 28, where a man suffered serious injuries.
Robinson reportedly left the UK shortly after the incident and was arrested on suspicion of grievous bodily harm.
The assault, partly filmed and shared online, showed a man claiming self-defense, The Telegraph has reported.
The victim has since been released from hospital and provided a statement to police.
Written by B.C. Begley
