The two limbs of burglary
Burglary is defined disjunctively. Section 9(1)(a) criminalises entry as a trespasser with one of four specified intents: to steal, inflict grievous bodily harm, rape (now replaced by offences under the Sexual Offences Act 2003, though s.9(1)(a) continues to refer to rape), or do unlawful damage to the building or anything therein. Section 9(1)(b) criminalises the stealing or attempted stealing, or the infliction or attempted infliction of grievous bodily harm, by a person who has already entered as a trespasser. The distinction matters: for s.9(1)(a) the ulterior intent must exist at the moment of entry, whereas for s.9(1)(b) the relevant act or attempt must occur after entry. Crucially, s.9(1)(a) is an inchoate offence in substance—it punishes trespassory entry coupled with intent, irrespective of whether the intended crime is committed—while s.9(1)(b) requires proof that theft or violence actually occurred or was attempted.
Entry as a trespasser
Both limbs require that the defendant 'enters … as a trespasser'. 'Entry' is not exhaustively defined by statute. At common law, the insertion of any part of the body, however slight, sufficed. Early Theft Act authority suggested a similar approach: in Collins [1973] QB 100, Edmund Davies LJ stated that there must be 'an effective and substantial entry', though the facts (a man partially through a bedroom window, invited in by the occupant) left the precise threshold unclear. Later authority narrowed the requirement. In Brown [1985] Crim LR 611, the Court of Appeal held that the insertion of the top half of the defendant's body through a shop window constituted entry, even though his feet remained on the pavement outside. In Ryan [1996] Crim LR 320, the defendant became trapped in a window with only his head and right arm inside; the Court of Appeal held that this was sufficient entry, effectively abandoning any requirement that the entry be 'substantial'. The modern position is that any entry of the body, or arguably of an instrument used as an extension of the body, suffices, provided it is not de minimis.
Trespass requires absence of permission or authority to enter. A person enters as a trespasser if he knows or is subjectively reckless as to the fact that he is entering without permission: Collins, affirmed in Jones and Smith [1976] 1 WLR 672. The latter case established that a person may be a trespasser even if invited to enter for some purposes, if he enters with an intention that exceeds the scope of the permission. In Jones and Smith, the defendant entered his father's house (where he had general permission to enter) intending to steal a television set; the Court of Appeal held that his intention took him outside the permission and rendered him a trespasser. Similarly, in Laing [1995] Crim LR 395, the defendant, employed by a department store, entered parts of the store to which his access was restricted, intending to steal; his entry was held to be trespassory. The principle is that permission is construed in light of the purposes for which it is given, and an entry for an undisclosed and forbidden purpose is trespassory.
Building or part of a building
Section 9(1) applies only to entry into 'a building or part of a building'. 'Building' includes 'an inhabited vehicle or vessel', whether the person having a habitation in it is there or not (s.9(3)). Beyond that, the statute offers no definition. The courts have adopted a functional, common-sense approach. In Stevens v Gourley (1859) 7 CBNS 99, a structure was held to be a building if it had some degree of permanence and was of substantial construction. In B and S v Leathley [1979] Crim LR 314, a walk-in freezer container on site for two years, connected to electricity and resting on sleepers, was held to be a building. In Norfolk Constabulary v Seekings and Gould [1986] Crim LR 167, by contrast, a lorry trailer used for temporary storage was held not to be a building, despite having been in place for over a year; the decisive factor was its design for mobility and the lack of attachment to the land. The distinction can be fine and turns on degree.