Thanks all. As it happens no weighing of course, and indeed there seemed to be no enforcement of carry on size or number that I could see. Boarding took forever with all sorts of shenanigans going on to try to fit everyone's bags in the bins. I was very surprised. This is an issue for Air Canada (my main airline) and I was shocked that LH didn't handle it better (but of course this was just one flight, perhaps it does in general).