A jest dear boy, a jest ........
And not all security or customs are in uniform anyway - I had a meeting last week with a senior Police Offcier who was on duty but in civis..................
TBH the best people to spot a rat are those who used to be rats....... or are close enough to know. A trotskyite can spot a communist at 400 yards (and vice versa) whereas to you or I they may well look like members of the Labour Party.