52Evidence
(1)Any party to an appeal shall be entitled to adduce any lawful evidence.
(2)The Commissioners may summon any person (other than the appellant) to appear before them and give evidence, and a witness before the Commissioners may be examined on oath:
Provided that any agent or servant of the appellant, and any other person confidentially employed in the affairs of the appellant, may refuse to be sworn or to answer any question to which he objects.
(3)A person who after being duly summoned—
(a)neglects or refuses to appear before the Commissioners at the time and place appointed for that purpose, or
(b)appears, but refuses to be sworn, or
(c)refuses to answer any lawful question concerning the matters under consideration,
shall incur a penalty not exceeding £50 :
Provided that the penalty imposed in respect of any offence under paragraph (b) or paragraph (c) of this subsection shall not apply to any such person as is within the proviso to subsection (2) above.