My understanding was that you had to fully admit the offence, the case be reviewed and it be decided that there was sufficient evidence to go to court, and then finally the person had to sign to say he/she admitted the offence and furthermore sign to say they understood what a caution was?
Of course if somebody doesn't understand what's being said etc then if 17 or over they should have an appropriate adult - ususlaly somebody trained to deal with learning difficulties/mental health etc. What was the legal advice?
If someone refuses a caution it would automatically go to charge. I'm not entirely sure this is better because it would be a lot worse if convicted.