Fox3 I presume that you were on a shiny 10. In which case I find this very hard to belive. Even if the muppets had screwed up and not manifested you tbe ALM and Flt Eng would do a walk around even possibly the non operating pilot. 3 chances to spot the stowaways. Did you get on the wrong a/c and were still at Brize wben you got off? The clue would be no brandy sours!