Bussing inbound to another gate and outbound through the adjacent gate/door is to comply Home office and DFT dictate to ensure sterile security checks are maintained.
Yeap the UK agencies think we need screening about thirty times - frankly it’s way overboard imho.
Still we are where we are because of a small number of deluded and selfish loonies that have little empathy for others and even less for human life in general.