London mayor Ken Livingstone has agreed with Green Party proposals to make mobile phone masts subject to normal planning regulations and ban them from Greater London Authority and Transport for London land 'until such time as clear evidence is available relating to the possible health risks'. The government set up an expert group chaired by Sir William Stewart to advise on the safety of mobile phone technology. It reported in May and gave a clean bill of health to the technology, but advised that mobile phone bases should be subject to normal planning constraints.