(1) Every one commits burglary and is liable to imprisonment for a term not exceeding 10 years who—
(a) enters any building or ship, or part of a building or ship, without authority and with intent to commit a crime in the building or ship; or
(b) having entered any building or ship, remains in it without authority and with intent to commit a crime in the building or ship.
(2) In this section and in section 232, building means any building or structure of any description, whether permanent or temporary; and includes a tent, caravan, or houseboat; and also includes any enclosed yard or any closed cave or closed tunnel.
(3) For the purposes of this section and section 232,—
(a) entrance into a building or ship is made as soon as any part of the body of the person making the entrance, or any part of any instrument used by that person, is within the building or ship; and
(b) every one who gains entrance to a building or ship by any threat or artifice used for that purpose is to be treated as having entered without authority.