Before bear went down for the general anaesthetic, he was weighed and measured. He is 32.6kg (just under 72lbs or just over 5 stone) and 137cm tall (just under 54 inches or 4ft 6). He is no longer legally required to use the booster seat, which I think is something of a milestone for him. According to the NHS it is in the healthy range, but at the top end. I am not too stressed by that, as I suspect yet another growth spurt is about to happen.
There is actually quite a lot of useful stuff on the NHS website. One day I may use it.