21A(1)
A person commits an offence if—
(a) he has with him an air weapon on any premises; and
(b) he uses it for firing a missile beyond those premises.
21A(1A)
A person commits an offence if the person—
(a) is supervising the use and possession of an air weapon on private premises by a person under the age of 18, and
(b) allows the supervised person to fire any missile beyond those premises.
21A(2)
In proceedings against a person for an offence under this section it shall be a defence for him to show that the only premises into or across which the missile was fired were premises the occupier of which had consented to the firing of the missile (whether specifically or by way of a general consent).