Ian was embarrassed by this. He guessed that the person smiling at him had been on one of his training courses, or otherwise recognised him professionally.
There was one of those embarrassed lift silences lasting a couple of floors. Just before his destination Ian decided to break the silence: “I'm so sorry” he said, “You obviously recognise me, but I can't recall where we might have met?”. And in the instant of him saying this, with the man smiling bemusedly back at him, he realised who he was speaking to. Prince Andrew.