It could be that the infection (as this cancer is basically an STD) has more effect on younger women - fair assumption I guess
Now, the number of sexual partners has no impact apparently, so that knocks my theory a bit - but could it not be that poorer girls from deprived areas are more likely to be hooking up with infected young males (or 'chavs') from council estates?
This is what the sources on wikipedia (from the American Cancer Council in the US) suggest, and considering this is effectively an STD does that not explain the rich/poor divide quite well also? If it's caused primarily by an STD, how can the number of partners not make any difference to risk? This is how all STDs tend to go - 'deprived' people from council estates tend to be somewhat less cautious than their middle-class counterparts, it's well documented
Me smells a rat:
"Importantly, the results back up the need for the HPV vaccination to be given in schools at an age before they start having sex, especially among girls in deprived areas."