A trail of looted diamonds, greased palms and suspect arms deals suggests Britain is betraying its calls for action by other rich nations to stop shady corporate dealing in Africa, activists say. British Prime Minister Tony Blair launched a detailed plan devised by his Africa Commission this month to reverse the continent’s descent into poverty, including measures to ensure foreign firms did not profit from war and corruption. But critics say Britain has failed to meet previous commitments to clamp down on activities, from bribery to dubious deals in African conflict zones, casting it as laggard rather than leader in enforcing corporate responsibility.