A 51-year-old man has been arrested on suspicion of conspiracy to commit murder in connection with the shooting of a City trader.
Robin Clark, 44, who lives in Essex, was shot once in the leg as he got out of his car at Shenfield railway station on January 24.
The gunman ran off and left the scene in a car parked nearby.
A British Transport Police spokesman said: "Following an incident at Shenfield rail station on Friday 24 January, a 51-year-old man from Essex has been arrested on suspicion of conspiracy to commit murder.
"He has since been interviewed and released on police bail pending further inquiries."