LONDON (Reuters) – Britain’s biggest sportswear retailer, JD Sports Fashion, on Wednesday ousted longstanding executive chairman Peter Cowgill, saying its internal governance and controls had not kept pace with the firm’s growth. The FTSE-100 group said Cowgill, executive chairman since 2004, will step down from his role with immediate effect. It said that following a governance review it had decided to accelerate the separation of the roles of chair and chief executive. Helen Ashton, a JD non-executive director and chair of its audit and risk committee, will become non-executive chair, while …