By your definition, nope....still options to explore....still only unsure.....whose to say those big shiny jets aren't parked up at Exeter, Norwich or some other airport with instrument approaches but no CAS.....
Ok, now you're scaring me, and I dread the thought of coming across one of your students. Who's to say it isn't Stansted, Heathrow, Bristol, East Midlands, Birmingham etc.
By your reasoning you're still going to sit there trying to work out where you are, when the possibility is you COULD be an infringer. Is it going to hurt to make sure using the method I've said - NO. Is it going to get you out of trouble quickly - YES!
I'm not saying "shoot first, ask questions later" as you describe it - But I'll say it simply so that, hopefully, you start to understand what's been said because you seem to be having problems with that.
UNSURE OF POSITION - do what you've been taught by the likes of yourself.
HOWEVER
If you can't work out where you are by using those techniques, or you think, by the odd clue,
that you are somewhere you shouldn't be, then you are no longer unsure of position, you are
LOST
LOST = 121.5 / 7700