It's a test of your honesty as the FAO will rock up at the interview with your conviction history (if any), including cautions and that includes cautions you may have received as a kid. All these wife's tales that cautions only stay on record for five years is nonsense. It all stays on your record. Permanently!
In my interview I was asked about when I got pulled over in the car, no arrest or problems and even that was on record. I was only pulled over for a check as a car was stolen nearby simelar to mine. That was years ago too.