1. Sale And Letting On Hire
A person who sells or lets on hire a crossbow or a part of a crossbow to a person under the age of eighteen is guilty of an offence, unless he believes him to be seventeen years of age or older and has reasonable ground for the belief.
2. Purchase And Hiring
A person under the age of eighteen who buys or hires a crossbow or a part of a crossbow is guilty of an offence.
A person under the age of eighteen who has with him—
(a) a crossbow which is capable of discharging a missile, or
(b) parts of a crossbow which together (and without any other parts) can be assembled to form a crossbow capable of discharging a missile, is guilty of an offence, unless he is under the supervision of a person who is twenty-one years of age or older.
4. Powers Of Search & Seizure
(1) If a constable suspects with reasonable cause that a person is committing or has committed an offence under section 3, the constable may—
(a) search that person for a crossbow or part of a crossbow;
(b) search any vehicle, or anything in or on a vehicle, in or on which the constable suspects with reasonable cause there is a crossbow, or part of a crossbow, connected with the offence.
(2) A constable may detain a person or vehicle for the purpose of a search under subsection (1).
(3) A constable may seize and retain for the purpose of proceedings for an offence under this Act anything discovered by him in the course of a search under subsection (1) which appears to him to be a crossbow or part of a crossbow.
(4) For the purpose of exercising the powers conferred by this section a constable may enter any land other than a dwelling-house.
This Act does not apply to crossbows with a draw weight of less than 1.4 kilograms.
Hunting with a crossbow (or any other bow weapon) is completely illegal in the UK regardless of whether you are on private or public land. You may only use a crossbow for target practise.
The crossbow itself cannot be carried in public and a common sense approach should be adopted when transporting a crossbow.