British Airways Boeing 777-336ER G-STBH operated BA269 London Heathrow – Los Angeles with a three and a half hour delay in place of the usual A380 this evening. The aircraft then diverted via Las Vegas due to a security alert at Los Angeles, eventually arriving into Los Angeles after midnight. The return BA268 had already been delayed overnight due to a lack of rested B777-300ER crew at Los Angeles. We believe this is the first appearance of a British Airways B777-300ER at Las Vegas.