The Government has powers under the Immigration Act 1971 (“the 1971 Act”) to remove or deport persons on the ground that their presence in the United Kingdom is not conducive to the public good on national security grounds. Persons can also be arrested and detained under Schedules 2 and 3 to the 1971 Act pending their removal or deportation. The courts in the United Kingdom have ruled that this power of detention can only be exercised during the period necessary, in all the circumstances of the particular case, to effect removal and that, if it becomes clear that removal is not going to be possible within a reasonable time, detention will be unlawful (R v Governor of Durham Prison, ex parte Singh [1984] All ER 983).