The common law crime of arson has been abolished (Crimes (Criminal Damage) Act 1978 s3).
A person is guilty of arson if he or she commits one of the offences in sections 197(1), (2) or (3), and the relevant offence is committed by destroying or damaging property by fire (Crimes Act 1958 s197(6)).
Consequently, the elements of arson consist of:
The elements of the relevant offence under ss197(1), (2) or (3);
That the damage or destruction occurred by fire; and
That the accused intended to damage or destroy the property by fire. 
See the following topics for information concerning the elements of ss197(1), (2) and (3):
Where one of the relevant criminal damage offences is committed by fire, it must be charged as arson (Crimes Act 1958 s197(6)).
Consequently, indictments charging one of the offences in ss197(1)-(3) will be invalid if the property was damaged by fire (R v Wood & Ors  EWCA Crim 2436; R v Cooper (G) and Cooper (Y)  Crim LR 524).
However, these offences may be left as common law alternatives to a charge of arson.
 It is unclear whether the accused must intend to damage or destroy the property by fire, or whether a general intention to cause damage is sufficient. As a matter of prudence, it is assumed that the more specific intention is required. This is the approach taken in G Williams, Textbook of Criminal Law, 2nd ed, 913 and R v Cooper (G) and Cooper (Y)  Crim LR 524. But compare A Ashworth, "Transferred Malice and Punishment for Unforeseen Consequences" in P Glazebrook, Reshaping the Criminal Law (1978), 92.