BP's board and London-based executives were informed of widespread corrosion at the UK oil giant's Alaska field two years before the company was forced to shut it this week, citing "unexpectedly severe corrosion". On May 22 2004, Chuck Hamel, an advocate for BP workers in Alaska, took the charges directly to Walter E. Massey, chairman of the environment committee of BP's non-executive board of directors. In the letter, Mr Hamel told Dr Massey that in the previous four years BP employees and contract workers had brought to him concerns about safety, health and threats to the environment at Prudhoe Bay,...