UK 2015 election: searching for diversity

Why aren't there more minority MPs in the UK parliament? Black & Minority Ethnic (BME) communities are now over 8 million strong, equaling the population of Scotland & Wales combined. But they're politically underrepresented with only 27 BME MPs in a 650 seat parliament. To be representative of the UK's diversity, an estimated 117 candidates would need to win on May 7.