Hospital patients
8(1)A person is an exempt individual on a particular day if at any time on the day one or more of the following paragraphs applies to him—
(a)he is a patient who has his sole or main residence in a hospital;
(b)he is detained under Part II of the [1983 c. 20.] Mental Health Act 1983 in a hospital;
(c)he is detained under section 46, 47 or 48 of that Act in a hospital.
(2)“Hospital” means a health service hospital within the meaning of the [1977 c. 49.] National Health Service Act 1977.
(3)The Secretary of State may by order substitute another definition for the definition of hospital for the time being effective for the purposes of this paragraph.