A person alleged to be a party to arbitral proceedings but who takes no part in the proceedings may question—
whether there is a valid arbitration agreement,
whether the tribunal is properly constituted, or
what matters have been submitted to arbitration in accordance with the arbitration agreement,
by proceedings in the court for a declaration or injunction or other appropriate relief.
He also has the same right as a party to the arbitral proceedings to challenge an award—
by an application under section 67 on the ground of lack of substantive jurisdiction in relation to him, or
by an application under section 68 on the ground of serious irregularity (within the meaning of that section) affecting him;
and section 70(2) (duty to exhaust arbitral procedures) does not apply in his case.