I do think the security at UK airports is over the top. There's absolutely no room for common sense.
There are many other parts of the world where some airport staff and aircrew can still bring a pot of yoghurt or a bottle of water airside.
There's various stories that I've heard over the years such as engineers unable to bring milk or yoghurt though security as liquids, however they're perfectly OK if they're brought through frozen. Another (at LHR I think) was of an engineer trying to take his frozen ready meal though security, it was a hot day so said meal had begun to defrost, he had to open the (sealed) packet and drain off the liquid before being able to take the remaining frozen bit airside.
Whilst I'm sure there's some reasoning behind this, (I would guess that explosive liquids don't freeze), Engineers and Crew have plenty of other ways to bring down an aircraft if they so wish, we certainly don't need to resort to exploding yoghurt !