From 20th January 2004 it is an offence to carry an air weapon, whether loaded or not, or a replica firearm in public without permission.

The Anti-Social Behaviour Act 2003 also gives police greater powers to arrest people carrying such weapons. And has increased the maximum penalty to six months imprisonment.
 
This new legislation clarifies the position on replicas, imitations and air weapons and makes it clear that nobody should carry these types of firearms on the streets. It'll therefore be an offence to carry ball bearing guns in public.
 
Air weapons that use the self-contained gas cartridge system now require a firearms certificate.
 
Stricter controls have also been introduced over the sale of air weapons with the age limit being raised from 14 to 17 years old. It will also be an offence for an air weapon or ammunition to be given to a person under 17.
 
The legislation provides stricter controls on the use of such weapons. No-one under the age of 17 will be able to have an air weapon in their possession unless they are supervised by a person who's at least 21 or as part of a licensed shooting club.
 
But 14-16 year olds can use air weapons on private land as long as it's under supervision, with the owner's consent and shooting takes place within the land's boundaries.
 
Note: An imitation/replica firearm is defined as anything that has the appearance of a firearm whether or not it is capable of discharging a shot or bullet.