2SThe Parole Board shall include among its members—
(a)a Lord Commissioner of Justiciary;
(b)a registered medical practitioner who is a psychiatrist;
(c)a person appearing to the Secretary of State to have knowledge and experience of the supervision or aftercare of discharged prisoners; and
(d)a person appearing to the Secretary of State to have made a study of the causes of delinquency or the treatment of offenders.