Originally Posted by
sigma421
They can't so long as they wish to offer airside connections as there are people in that area without the right to enter the UK. GLA, EDI, ABZ etc. don't run airside connections so everyone in departures has entered from landside so has the right to walk back out again.
Would be interesting to understand the number of people doing airside international connections vs the number of people doing domestic/CTA arrivals. There is a chance the current setup optimizes for the wrong flow merely due to history.