In its decision in Sierra Leone v SL Mining Ltd,(1) the High Court confirmed that alleged non-compliance with the provisions of a multi-tiered dispute resolution clause (in particular, the submission of claims to arbitration prior to the end of a prescribed period of negotiation) is exclusively a matter of admissibility for the arbitral tribunal and cannot lead to a successful jurisdictional challenge under Section 67 of the Arbitration Act 1996. This decision confirms the scope of a London-seated tribunal's substantive jurisdiction under Section 30(1) of the Arbitration Act. It also confirms that initiation of arbitration proceedings, in apparent breach of a mandatory multi-tiered dispute resolution clause, may be valid where settlement of the dispute is deemed impossible within the remaining prescribed period.