Dave ... I believe that this new security charge at Liverpool is aimed at paying for enhanced security, as well as reducing the time which passengers have to spend in queues at security checks.
My understanding is that passengers will have to pay the new charge at a ticket machine, and then insert that ticket in a separate turnstile, before being able to proceed through passport control and security. Presumably this could mean joining one queue at the ticket machine, before joining a second queue at the turnstile, followed by a third queue at passport control, and then a fourth queue at security.
However, the income generated from the security charge may help ensure that passengers continue to benefit from shorter queues at security, even if that does mean joining completely new queues beforehand in relation to the collection of that charge. If this charge is essential, one would have thought that there might have been better ways of collecting it, such as at the time of booking, thereby reducing the need for all these queues.
Hopefully it is not something which will catch on elsewhere, but the financial burdens of increased security measures are undoubtedly having an effect on many airlines and airports. Meanwhile it does sound as though passengers at Liverpool may have to endure increased expense, inconvenience and queues.
David