9(1)When any question arises under this Act whether a person is exempted from the provisions of section 5, 6 or 7 of this Act it shall be for the person asserting that he is exempt to prove it.
(2)A person is not to be treated as ordinarily resident in Great Britain for the purposes of the exemption in section 5(4)(a) of this Act or in Northern Ireland for the purpose of the exemption in section 6(4)(a) of this Act at a time when he is there in breach of—
(a)an exclusion order; or
(b)the [1971 c. 77.] Immigration Act 1971 or any law for purposes similar to that Act in force in the United Kingdom after the passing of this Act.
(3)In each of those exemptions “the last three years” is to be taken as a period amounting in total to three years exclusive of any time during which the person claiming exemption was undergoing imprisonment or detention for a period of six months or more by virtue of a sentence passed for an offence on a conviction in the United Kingdom or in any of the Islands.
(4)In sub-paragraph (3) above—
(a)“sentence” includes any order made on conviction of an offence;
(b)two or more sentences for consecutive (or partly consecutive) terms shall be treated as a single sentence;
(c)a person shall be deemed to be detained by virtue of a sentence—
(i)at any time when he is liable to imprisonment or detention by virtue of the sentence but is unlawfully at large; and
(ii)during any period of custody by which under any relevant enactment the term to be served under the sentence is reduced.
(5)In sub-paragraph (4)(c)(ii) above “relevant enactment” means section 67 of the [1967 c. 80.] Criminal Justice Act 1967 and any similar enactment which is for the time being or has (before or after the passing of this Act) been in force in any part of the United Kingdom or in any of the Islands.