Appointment of arbitrator
10. A notice under article 9 requiring arbitration under the 1986 Act shall cease to be effective three months after the date of the service of that notice unless before the expiry of those three months—
(a)an arbitrator has been appointed by agreement between the parties, or
(b)(in default of such agreement) an application has been made by the tenant or the landlord under paragraph 1 of Schedule 11 to that Act for the appointment of an arbitrator,
for the purposes of that arbitration.