Transiting through LHR tonight en route from DUS to NCL and after clearing immigration I had my photograph taken as per usual by the BAA staff. I was also given a red sticker labeled "Security" with today's date and told not to lose it / keep it until I'd boarded my next flight.

I asked what it signified and was told "I don't know. We've just been told to do it" which sounds somewhat Orwellian. I asked at the Flounge and they hadn't seen it before but took a guess that it was to signify that my iPod was charged and worked - which seems unlikely as I'm flying to Newcastle.

Anyone else encountered this and can shed any light?