I personally think that the DFT need to teach there (sic) security staff about the other trades within an airport.
Think you will find all the screening staff at UK airports are employed by either the Airport or as contractors to the airport and not by the DFT. DFT set the rules and audit the system and the screening staff have to abide by the rules. However, as in all things these days, sometimes the element of common sense is missing. Maybe something to do with the constant surveillance the staff are under - get it wrong and you could lose your job.
No doubt trade organisations have made and are making representations about some of the regulations, but I'm sure DFT want to ensure they are "bomb-proof" (pun intended) if anything goes wrong.
Suzeman