Six Bomb Blasts Around Central London
If they cannot find somewhere else to go then they should be detained until they go, I would not want to send anyone to their deaths, but I don't see why we should provide open access to the country until people leave.
A sizable part of the 9-11 terrorists had either lived or was living in the West (Germany) when they committed their attacks. The Madrid attacks were perpetrated by Moroccans living in Spain. Britain seems long to have thought itself safe from terrorism of the islamic variety by being soft on various islamic extremists (Finsbury Park mosque).