Those of you who don't work for BA are missing a crucial point. Crew ARE entitled to take bottled water off the aircraft (max 2 x 500mL). Crew ARE allowed to purchase minatures and minerals. The question raised is 'how long are you supposed to keep your receipt?'
Anything else is theft, granted, but how can police come into someone's house, find a generic item such as a minature of alchohol and immediately accuse the person - regardless of ANY OTHER INVESTIGATION - of stealing. Where do you draw the line? Do you have the receipt for every single thing you have purchased?