@Heathrow Harry - Indeed, which gives even less excuse for the security systems to create a target rich environment with extensive 'Disney style' queues.
The security staff know their throughput rate, they know the demanded throughput from the number of pax due to go to the gates in each hour; so either staff up to provide the required throughput rate or cancel flights due to lack of security capacity to avoid creating crowds of 'targets'.
The real issue again is that the willingness to increase security inspections is not matched by a willingness to pay for the required security capacity. As the government is now saying that the current raised security level will be the case for some time then there is no excuse not to increase security capacity