So, I turn up at the headquarters of a major company in central London. The “staff” entrance is the same as normal, but on the other side of the door marked “visitors” there is an empty chair.

I tap on the glass and eventually the security guard sees me, wanders over to the door and climbs on the chair to free a bolt at the top. He opens the door but does not let me cross the threshold. Instead, he asks me what I want?