Heavy rain and sleet could cause tunnels beneath Euston in London to collapse and endanger HS2 activists living in the underground passages, a rescue expert has warned. It follows 'liquid mud' pouring in on Friday, amid fears the green activists - including veteran eco-warrior Swampy - could be 'buried alive' in the tunnel. Cherry pickers arrived this afternoon to dismantle ramshackle tree houses built by the activists. Exclusive video for MailOnline also shows Swampy complaining that a bailiff is stepping on his arm in the grim tunnel. The veteran activist, 48, whose real name is Daniel ...