It's not the job of UK to make MQM to account. The primary responsibility lies with Pakistan. To begin with how can you point fingers at UK when -
- for decades millions from Karachi and other Mohajir enclaves have boted for Altaf bhai.
- for decades MQM have ruled Karachi and at times even were part of President Musharaf's government
- for decades the MQM have been the elective voice of the Mohajir community which claims to be the best educated in Pakistan
Given these realities you can't expect foreign governments to clean your mess. It is Pakistan and in particular the MQM voters who have think about what they voted in for so long. It is possible that Altaf has offered his services to UK in which case he is a asset since they knew how much MQM had influence over Karachi. This again raise the question that who voted him and his party given it's acknwledged links with India and to terrorism like the Baldia fire.