We've all noticed the long queues outside women's toilets at high trafficed venues, this is because women take between two and five times as long to go to the toilet (for a variety of reasons), but, being a guy, I'd never really thought about it. New York isn't the first state to do this, California introduced a law back in 1987 and a number of other states followed suit in the 1990s. The problem has been that many of the original laws governing toilet facilities were written when men were the only ones in power and who were the more likely to be out and about, a quote from the article demonstrates this best:
And it has been argued that the longtime lack of a lavatory designated for female U.S. senators symbolized the exclusion and, later, grudging inclusion, of women from that body. Until 1993, when senatorial women's restroom was constructed outside the Senate chamber beside the senatorial men's room, female senators were obliged to descend to the first floor of the Capitol building and line up with tourists for a public women's restroom.
All praise to potty parity. I have no idea what the law is in the UK, maybe someone needs to look into it.