“Accordingly, although a Chairman has very wide powers to make case management decisions, where a full Tribunal has been convened (and that is whether it is pre-hearing review or a full hearing) then the full Tribunal must make the relevant decision in relation to any case management issues that arise. The power conferred by rule 10, allowing a Chairman to make an order ‘at any time’ does not mean that the Chairman can, in the course of proceedings where a full panel has been convened simply take decisions independently of the lay members.”