Suzie,
Huckster is absolutely correct.
The case highlighted on the TV is going to certainly cause some confusion. Essentially, regarding criminal convictions, you must disclose unspent convictions under the Rehabilitation of Offenders Act 1974. Cautions were recently (December 2008) brought within the remit of the ROA, and become spent immediately. Therefore, you can answer any question as only relating to unspent convictions.