A constable of a police force in England and Wales may arrest a person in England and Wales without a warrant if—
A constable of a police force in Scotland may arrest a person in Scotland without a warrant if—
Without prejudice to the generality of subsection (2)(b), it would not be in the interests of justice to delay an arrest for a purpose mentioned in that subsection if the constable reasonably believes that, unless the person is arrested without delay, the person will obstruct the course of justice in any way, including by seeking to avoid arrest or interfering with witnesses or evidence.
A constable of a police force in Northern Ireland may arrest a person in Northern Ireland without a warrant if—
The power conferred by subsection (1) or (2) may be exercised by a constable appointed under section 24 of the Railways and Transport Safety Act 2003 or under section 55 of the Energy Act 2004 in England and Wales or (as the case may be) in Scotland.
The following provisions apply in relation to an arrest under this section by a constable of a person suspected of having committed a specified offence in England and Wales or in Northern Ireland—
Where a constable is arresting under this section a person suspected of having committed a specified offence in Scotland, the constable has the same powers as a constable of a police force in Scotland would have if arresting the person for the offence in Scotland.
In this section—
“constable of a police force”, in relation to Northern Ireland, means a member of the Police Service of Northern Ireland or the Police Service of Northern Ireland Reserve;
“specified offence” has the meaning given by section 137B.