I have been through Heathrow crew checks many times and with the exception of x-raying the crew luggage I believe them to be a waste of time.
Most of the support drivers(fuel,mail,food etc.) only have their passes checked, the vehicles are not inspected!
I often wonder what they expect to find in a pilots bag as the most dangerous weapons on board are at the end of a pilots wrist!! All this rot about penknives and the like is unbelivable - if I wanted to whack somebody I would reach for the flight deck fire axe!