For Afghanistan, Pakistan, and the Middle East in general, yes, the language and some kind of cultural knowledge. The same reason why a lot of Vietnamese, Laotian, or Lebanese refugees went to France some decades ago. They need to know about the quality of life, which happens mostly if there is some kind of cultural contact.

Quality of life in the UK is good, don't get me wrong, but not orders of magnitude better than what they could find on the continent.