The most galling thing about this case is that the two 'UK citizens' filmed fighting in Najaf actually fled Iraq as children and sought sanctuary in the UK. Yet now they have returned there to fight the forces who deposed the regime they fled.
It is akin to a German Jew fleeing Germany in the 30s only to return in 1945 to fight the allies.
These people clearly regard British citizenship as no more than a flag of convenience to be used for its benefits but with no idea of its responsibilities. It would be nice to think that they will face a very long jail term if and when they return, followed by permanent expulsion from the country. But just like those caught in Afghanistan or the Afghan plane hijackers - how likely is that?