On taboo grounds? A primer from '08:
http://www.independent.co.uk/news/s...s-getting-married-scientists-say-1210072.html.
The research is still out on whether British Pakistani communities are at any greater risk compared to other people marrying their first-cousins from other demographics. Basic genetics make the risks tolerable. The current government, before May admittedly, has received evidence on the matter and no changes are on the horizon as a result.
But as I said and happy to expand: if the law changes, making the practice illegal, then a further legal change will apply to our immigration rules. For as long as the law stands, I see no reason to discriminate specifically against a particular case of marriage that's recognised by the state.