47Custody of prisoner in transit, &c
(1)The following provisions of this section apply in relation to times when the prisoner is subject to a warrant under any provision of this Part, or any corresponding provision of an Act of the Scottish Parliament, but is not in legal custody under the Prison Act 1952 (c. 52), the Prisons (Scotland) Act 1989 (c. 45) or the Prison Act (Northern Ireland) 1953 (c. 18(N.I.)).
(2)The prisoner shall be deemed to be in the legal custody of the relevant Minister at any time when, being—
(a)in the United Kingdom, or
(b)on board a British ship, a British aircraft or a British hovercraft,
he is being taken to or from any place or is being kept in custody.
(3)The relevant Minister may, from time to time, designate a person as a person who is for the time being authorised to take the prisoner to or from any place or to keep the prisoner in custody.
(4)A person so authorised has all the powers, authority, protection and privileges—
(a)of a constable in the part of the United Kingdom in which that person is for the time being, or
(b)if he is outside the United Kingdom, of a constable in the part of the United Kingdom to or from which the prisoner is to be taken.
(5)If the prisoner escapes or is unlawfully at large, he may be arrested without warrant by a constable and taken to any place to which he may be taken under the warrant referred to in subsection (1).
In this subsection “constable”, in relation to any part of the United Kingdom, means—
(a)a person who is a constable in that or any other part of the United Kingdom, or
(b)a person who, at the place in question, has under any enactment (including subsection (4)) the powers of a constable in that or any other part of the United Kingdom.
(6)In this section “the relevant Minister” means—
(a)in relation to a person who is, or is to be, detained in England and Wales or Northern Ireland, the Secretary of State, and
(b)in relation to a person who is, or is to be, detained in Scotland, the Scottish Ministers.