"A caution is an admission of a criminal offence."

"Cautions" in the British system involve a kind of plea bargain, in which someone is offered by the police the alternative of being charged with a view to prosecution, or of making a formal admission of guilt and being given a caution, with no court proceedings. Typically this happens where the offence involved is relatively trivial, or where there is a good chance that the prosecution would not stand up in court, or that the Crown Prosecution Authority might decide not to go ahead with a prosecution.

As with all plea bargains, there is no particular reason to believe that an admission of guilt is genuine, since the accused person has been offered a very powerful inducement to make such an admission.