I don't work for BA but the safety bulletin mentioned earlier has been circulated around the company that I work for. One thing drilled into new employees and current ones too is not to approach an aircraft until it is safe to do so. This is decided by the captain/FO when they switch off the anti-collision lights, then and ONLY THEN do we approach the aircraft to chock etc... The only exception being if the a/c has unserviceable APU when only the nose of a/c is approached as described before. Very rarely do I see this procedure not followed.
Ground staff are by no means perfect and mistakes are bound to happen when airlines put pressure on us to turn around a/c in 25mins with 160+ bags off-loaded and 160+ bags loaded. Just a shame that it takes something like this to remind some of the dangers.