Education has been suggested, but you can’t educate the uneducable.
If people won’t leave their own obvious cultures behind when they leave their own country, they are not likely to leave behind those cultures and practices which can easily go undetected. And even those born in the UK are doubtless bought up on “tales of the old country.”
This barbaric practice is carried out because it’s what their backwards culture and religion expects, and it’s done by the backwards to the future backwards, who will probably carry on the tradition when they have children of their own.
If we hadn’t let so many of these people into the country, we would probably never have heard of FGM. Or maybe we’d think it’s a lads mag!
I would guess the reason for lack of arrests (aside from the fact its hard to detect) is because it’s so much easier to pretend it doesn’t happen, rather than risk alienating those we mustn’t upset, for fear of being branded racist.