I would have to agree with that observation about inbound screen bangkokeasy, what are they checking for?? A couple of weeks ago (Fri 22 June), all flights coming in and arriving at gates on the E arm were being screened.
The thing that really gets me about LHR is its location: almost everyone who uses it has to go round the M25 (what a good idea), and being to the west of London means just about every day, incoming flights use the Thames through central London as their approach. It's great for tourists coming in first time to be able to see London in all its splendour, and when I worked in the city it was great summer lunch times at the pub in Hays Galleria (by HMS Belfast), couple of pints, watching the planes go by, but in these troubled times, imagine the mess you could make from a roof top with a SAM.