An enhanced CRB check will show all cautions and convictions plus any other information which a senior police officer (or other relevant agency) deems to be appropriate.
Following the investigation into the Soham murders, police forces throughout the UK have been encouraged to ensure that all allegations of misconduct (particularly, of course, sexual misconduct) are included in an enhanced CRB check. (Ian Huntley had previously been accused of sexual offences but had never been convicted. Those allegations were not included in his enhanced CRB check).
That means that many people now find unproven allegations included on their CRB checks, even though they might previously been unaware of them. For example, a teacher posted on here to say that his enhanced CRB check had shown an allegation of 'grooming', even though he'd never been questioned about, or even made aware of it by the police. Similarly, I know of a teacher who found that her husband's conviction for a sexual offence (which she was aware of) appeared on her enhanced CRB check.
So there would seem to be a good chance that your friend's brush with the law might well show up on his enhanced check.
Chris