As you know your on my friends list and I follow quite a lot of your threads, from what I've read your and intelligent and honest poster so as others have stated I have no reason to believe you have made this story up and therefore I take your account of what happened as fact including your feelings of suspicion and paranoia at the time.
I don't know that much about BEK's so I've just done a quick Google search to gen up on them; Am I correct in thinking they are basically kids with fully black eyes who knock on peoples doors asking to use the toilet or "come in for a talk" and basically frighten the life out of the homeowner with their strangeness?
At the end of the day I wasn't there personally to witness what happened so I can only go off your thoughts and opinions, judging from what you said it seems like a very strange experience.
With regards to the medical aspect, yes, it's possible for the entire pupil to be dilated thus giving the impression of having a completely black eye and as others have mentioned certain illegal substances can also do this.
I don't believe in your case however that the kids were on drugs.
Lots of things seem strange like the kids tone of voice, pseudo-accent, choice of words (i.e. mate) but unfortunately I don't think we will ever be able to get to the bottom of what happened.
Unless they return! Which if they do I'm sure we will be the first people to hear about it...
At the end of the day, it seems like a highly unusual experience to me and I'd go with the thought that something was definitely not right.
edit on 3/10/10 by Death_Kron because: (no reason given)