I think there is a few who don't realise how drink and how long it takes to leave the body, if the guy has been on a session for a few days, it is the holidays it would be easy for him to be maybe even 10 times the limit after going to bed and with the liver only being able to process 1 unit of alcohol per hour then easily be 4 times the limit in the morning without realising it, I didn't know all this years ago but I do now, that is why I would give the lad a chance if all was ok before, but I would make sure he was educated fully on how drink works, and no I wouldn't have let him drive home I would have driven him home and then had a long hard think on how to proceed, then went and seen him that evening or something along those lines, at this point when he was sober and I was calm I would then decide what to do. and he would be on his very last warning from that moment on.