The British government Sunday restored to “severe” the terror threat level that was raised to “critical,” its highest, Saturday, the day after a terrorist bomb blew up a Tube train drawing into the London station of Parson’s Green injuring 30 people. Also Sunday, anti-terror police raided a second house in Stanwell near Heathrow airport. Since ISIS claimed the attack, DEBKAfile’s counterterrorism sources report that Scotland Yard and MI5 suspect a terrorist network is at work in the country, which struck earlier this month in Manchester and has since gone into action in the Greater London area. They have deduced that its cells are interconnected Lego-style. The fact that only two suspects have been rounded up since the Friday attack indicates that the investigation is still groping in the dark.