Again, to answer that, the U.K. has had legislation on equal pay and sex discrimination since the early 1970s. This legislation is effective as far as it goes in individual cases, in that if individual cases are taken, they're often won. But it's ineffective in that it hasn't tackled the underlying problem, which is that individuals often can't afford to take the cases or don't have access to the knowledge they would need.
Class actions like in the U.S.—I'm not normally a fan of U.S. social policy—and using statistical evidence rather than individual evidence on comparability would probably be needed in order to close the pay gap we now have. It has closed a long way, but it is still a considerable sum of money over the life course of an individual woman compared to an individual man with equal levels of qualification, doing equal jobs.