I'm fairly certain the concerned individual wasn't dumb enough to have tried this. Not in LHR... At least I hope.
It's most likely a case of a forgotten item in the bag, or even a metal knife from the meal tray (those you couldn't cut mint jelly with) which slipped and fell in the flight bag.
Still, thanks to the greatest airport security team of them all for saving the day from this obviously dangerous maniac...
said his fault and they just threw it in bin and wished him a safe flight .
That's fine and dandy in a place where logic and common sense have any degree of existence. This is LHR staff security we're talking about. The ones taking your bag apart to confiscate and scold you about the deadly >125ml tube of toothpaste you nefariously tried to bring onboard while waving turban wearing ramp staff right through.