Banking's "macho culture" is the biggest barrier to women reaching the top, according to a report published arguing that quotas for women executives are not the solution for Britain's unbalanced boardrooms.The Institute of Leadership and Management warned that organisations are "filtering out" top female talent at all levels…Charles Elvin, its chief executive, said enforced quotas to increase the number of women executives are "patronising" and unpopular with both sexes. Instead he called for changes to attitudes and management processes, more flexible working, and a genuine meritocracy…Rather than a single "glass ceiling",the ILM sees a series of barriers that filter out female talent at each stage of the management hierarchy, mainly due to the attitudes and behaviour of senior managers. [refers to Associated British Foods, WM Morrison, Shell, Tate & Lyle, Schroders]