‘Excuse me, but are you self-serving?” The question took me by surprise, and I could only apologetically ask my interlocutor to repeat it from behind his mask. “Are you self-serving?” Caught totally off guard, I looked at him blankly for a few seconds and wondered if I might be entertaining angels unawares. An odd-looking angel, I thought, with his basket full of shopping; the God of surprises strikes again. 

Then the penny dropped. I was in the queue in Sainsbury’s, and my unknown friend was wondering whether I wanted to go ahead of him and use one of the available self-service machines that such companies have introduced to keep waiting times down (and presumably payroll costs as well). He was anticipating being served at the counter that stocks the spirits, cigarettes and lottery tickets, and hadn’t wanted to hinder my progress.