LONDON (Reuters) -The union representing some of England’s head teachers, deputy and assistant heads said on Monday its members failed to meet the legal turnout requirement for industrial action and will consider a re-run of ballot due to postal disruption. The union, which balloted approximately 25,500 eligible members in England and Wales, said that based on its own surveys many members had had trouble receiving their ballot papers. The postal system in Britain has recently been disrupted by strikes. “We have to conclude that our democratic process has been compromised by factors outside of …