Sch 8 para 6
If any member of the Tribunal is unable to act in any case a deputy may be appointed by the Lord President of the Court of Session or the Secretary of State, as in the case of the appointment of the member in question; and, if the member is the chairman, the deputy shall possess the professional qualifications required for the office of chairman, and, if the member is the practitioner member, the deputy shall be appointed from the same panel.