The chief executive of Wal-Mart Stores (WMT.N) has emerged as an unlikely voice for gay rights after the Arkansas state governor heeded his call on Wednesday to reject a much-criticized bill. For years it has resisted calls by labour groups to pay a “living wage” and its move in February to increase pay to at least $9 an hour was viewed by many analysts as driven by competition for workers in a tight labour market as much as social concerns.