Have you considered what the thoughts were of the unfazed Begum were when she saw the severed heads, of her organisation's handwork in dustbins."Oh dear. I do hope hubby and his mates gave these enemies of ISIS due process and a fair trial" If the owners of those heads were kurdish,Iraqi or Syrian then it is down to those to dispense justice how they feel fit.
If you were caught smuggling drugs into Manila Airport you would be tried ,and if convicted, shot. Nothing that the British Embassy can do. Their country. Their rules. Why should the UK pay for an expensive trial,lining some briefs coffers with oodles of legal aid money? Would you be prepared to donate to crowd funding for her trial?