A third man has been arrested in connection with last week’s attack on a London commuter train near Parsons Green underground station.br br The 25-year-old was detained in Newport, south Wales.br br In what has been described as a “fast moving investigation”, police are questioning an 18-year-old arrested at Dover on Saturday and a 21-year-old detained in West London.br br The home made bomb sent flames shooting through a packed railway carriage during Friday morning rush hour. Thirty people were injured.br br It’s the fifth major attack regarded as a terrorist incident in Britain this year. Self-styled Islamic State has claimed responsibility but police say there is no evidence of direct IS involvement.