Generally he's been wearing a t-shirt and fleece but every now and then he has a video call with a client and wears a shirt. The stunt shirt hangs on a hanger on the handle of his wardrobe door. It gets worn for maybe 30 minutes at a time up to twice a week so lasts for two or three weeks before going in the laundry basket.
It's going to be a wrench for him going back to the office as he clearly dislikes work shirts, he runs straight upstairs after the call finishes to get back into his t-shirt and fleece. 
A bit like me and shoes, I've barely worn shoes for a whole year and now they feel wrong. 