Independent: To find Dr Caroline Lucas, the first-ever official leader of the Green Party, you catch an environmentally friendly train or Tube to London Bridge station, and then take a carbon-neutral walk for the couple of hundred yards to the old Hop Exchange on Southwark Street. Close up, from the pavement, the listed building seems past its best. But stepping through its iron gates reveals a breathtaking atrium of white walls, curved windows and green iron galleries, with a glass roof above the …