Consider this security chasm.
On a number of occasions recently I have found myself in the flight deck with a 6ft Muslim sat behind me (who I have not met before) with his right hand next to the fire axe, who has not yet had an airside pass issued.
How can this happen?
As new cabin crew members they are encouraged to sit on the jump seat for the first few sectors. Heathrow security often takes a few weeks processing airside applications, so in the meantime they have none. After only a few short weeks training any Tom, Dick or Mohammed can be off the street and in the cockpit of an airliner. (But not my wife of course).