It turns out that I am not very good a miming during rehearsal. I managed to walk off the stage before one of my songs was finished, and mimed lines I don't sing -- two things I have never done while actually singing the songs. But I have no usable voice so I will continue miming until I am confident I won't damage my voice.
I flew to London from Tokyo last Monday. The air on a plane is always drying, but this seemed particularly bad with many people coughing because of dry throats before we landed. I also ended up dehydrated as I was ill during the flight, which really didn't help my throat. I didn't speak much during the flight, but I did chat to my neighbour for 30 minutes or so at the start, and I probably should not have done. My throat was dry and scratchy when I arrived in London, but I wasn't overly concerned.
By day 2 of my trip the dust in the city and the dryness in the air meant I could barely sing "Happy Birthday" at the event I attended. I was with friends all day so did a lot more chatting than I do on a normal day at home. By the end of the day I was hoarse, and by Wednesday, I had no voice at all. At that point I stopped talking, certainly did not try to sing, and hoped that with vocal rest and good hydration that my voice would recover quickly.
It's now Monday and I still can't sing. I do have some of my voice back, so I did speak lines yesterday, but I would not risk singing. Today I have been able to do vocal warm-ups in my chest voice, but my head voice is still missing. Hopefully it comes back soon!