Infancy as a Defence
Children under the age of ten cannot be convicted of a criminal offence. This also means that any adult cannot be an accessory to a crime committed by a child: Walters v Lunt  2 All ER 645.
Historically, children over the age of ten were rebuttably presumed incapable of criminal responsibility unless the prosecution proved otherwise. This was abolished by the Crime and Disorder Act 1998, s 34. Some argued that it was still possible to avoid liability by proving that the child-defendant was incapable of criminal responsibility. However, this possibility was dismissed in R v JTB  UKHL 20.