I am not so sure they are. Are the the captors of them a legitimate and recognized force?
I agree with you if they were captured by an armed force of a country during a battle.
I am not so sure the people doing the capturing are a legit force.
Either way I think they would do best by not executing them.
And therein lies the cruz of the problem. Who is the legitimate government of Libya? Either way, the Brits took a huge gamble sending soldiers out of uniform into the middle of a civil war. Will the rebels execute them? I doubt it. But Britian already had a problem with how cozy they’ve been with Gaddafi. Now it’s worse.