I would have brought her back and made her face justice. Better to have her under control in a British prison than allowed to carry on with her life elsewhere.
I share some of Shmmee's views that at 15 she was potentially vulnerable, and that may have been forgivable had she shown any remorse, but she hasn't. She still poses a threat in my eyes, wherever she is. Just because she isn't in the UK it doesn't mean that she can't hurt us from afar. There is no way she should be allowed to integrate back into normal life, and the best way to do that would have been to lock her up. That said, hopefully the government have a plan to monitor her actions abroad (hopefully she won't just be set free).
Again no one is making excuses for her. To suggest she deserved some protection as a 15 year old is a reason not excuse and to say she has been traumatised by her experience is a reason not an excuse. Why is everything so black and white?
Would be under counter-terrorism laws, but I'm not sure what the specific charge would be. Senior counter-terrorism officials in both the Met Police and MI6 have both come out and said she could be arrested on arrival, investigated and potentially charged (obviously pending outcome of any investigation).
If she wasn't, I dare say with her profile she wouldn't last 5 minutes on the streets.