3 years and 9 months, heading up for 4, at that age old enough possibly to talk about bodily functions and toilet training. I would have thought, for the child being in a soiled nappy feels uncomfortable and that would register once they do it in the toilet. I've read about children starting school in nappies, too much for teachers to deal with. I remember when mine were that age, the pressure felt relentless to get them out of nappies, female counterparts were always well ahead, I felt my boys were latish in that respect aged between 2 and 9 months to 3 before we got there on a process that seemed interminable. It was expected that children be out of nappies before entering the school nursery around 3 and 3 months, and to my knowledge, all were. My grandson was probably 3 when he was toilet trained, his sister a full year younger. It does seem these days that toilet training isn't something some parents will give over a lot of time too. Would they allow you to help maybe?