That group beheaded US journalists James Foley + Steven Sotloff and British aid workers David Haines + Alan Henning.
High Court ruled in favour of UK gov last month but an appeal to Supreme Court is being sought. No decision yet. No time frame for one either...
Once they've left, the US has far less power to decide the fate of detained Isil fighters - including the Beatles.
'Worst of the worst' as one well-placed US source put it to me. Another said the Beatles "have American blood on their hands”.
1) Guantanamo
2) Detention by US military in Middle East
3) Detention by an ally in Middle East
The last two carry much more risk of escape than the first. Hence interest in Guantanamo.
Don't forget Trump is a fan. Here he is pledging to fill it with "bad dudes" during campaign. (He formally kept it open in Jan 2018)
Part of the justification for allowing the Isil Beatles to possibly be executed in America was to avoid Guantanamo.
But bottom line - there is now a real chance two former British citizens will be in Guantanamo by end of the year.
*ends*