To save the mods some work and to perhaps bring this back into the realm of all things BA, I had a similar experience last week on a BA flight. I took a couple of pictures of it at the time but decided against starting a new thread.

I had a similar experience to the OP and was surprised that the cabin crew on the upper deck were so lax about the situation especially given that the seat in question was so close to the nearest usable exit for all of us on the upper deck.

After handing out the jackets/coats prior to landing they sat down leaving a coat hanging over the footstool right in front of the emergency exit and a whole host of items on top of the side locker right in front of the exit ready.