In the 1971 Act, after section 28, insert—
(1)A constable or immigration officer may arrest without warrant a person—
(a)who has committed or attempted to commit an offence under section 24 or 24A; or
(b)whom he has reasonable grounds for suspecting has committed or attempted to commit such an offence.
(2)But subsection (1) does not apply in relation to an offence under section 24(1)(d).
(3)An immigration officer may arrest without warrant a person—
(a)who has committed an offence under section 25(1); or
(b)whom he has reasonable grounds for suspecting has committed that offence.
(4)An immigration officer may arrest without warrant a person—
(a)who has committed or attempted to commit an offence under section 25(2); or
(b)whom he has reasonable grounds for suspecting has committed or attempted to commit that offence.
(5)An immigration officer may arrest without warrant a person (“the suspect”) who, or whom he has reasonable grounds for suspecting—
(a)has committed or attempted to commit an offence under section 26(1)(g); or
(b)is committing or attempting to commit that offence.
(6)The power conferred by subsection (5) is exercisable only if either the first or the second condition is satisfied.
(7)The first condition is that it appears to the officer that service of a summons (or, in Scotland, a copy complaint) is impracticable or inappropriate because—
(a)he does not know, and cannot readily discover, the suspect’s name;
(b)he has reasonable grounds for doubting whether a name given by the suspect as his name is his real name;
(c)the suspect has failed to give him a satisfactory address for service; or
(d)he has reasonable grounds for doubting whether an address given by the suspect is a satisfactory address for service.
(8)The second condition is that the officer has reasonable grounds for believing that arrest is necessary to prevent the suspect—
(a)causing physical injury to himself or another person;
(b)suffering physical injury; or
(c)causing loss of or damage to property.
(9)For the purposes of subsection (7), an address is a satisfactory address for service if it appears to the officer—
(a)that the suspect will be at that address for a sufficiently long period for it to be possible to serve him with a summons (or copy complaint); or
(b)that some other person specified by the suspect will accept service of a summons (or copy complaint) for the suspect at that address.
(10)In relation to the exercise of the powers conferred by subsections (3)(b), (4)(b) and (5), it is immaterial that no offence has been committed.
(11)In Scotland the powers conferred by subsections (3), (4) and (5) may also be exercised by a constable.”