Photographing people at work asks a question first, out loud, in whatever language you can manage. The answer here was yes, and then they carried on and forgot I was there, which is the only part that matters.
Available light, 50mm, no flash. A flash would have bought me a stop and cost me the entire atmosphere, along with any chance of being forgotten about.
I sent prints afterwards. It takes an extra ten minutes and it is the difference between taking a picture and being given one.