Where under this Act any difference (other than a difference to which the provisions of the Act of 1965 apply) is to be determined by arbitration, then, unless otherwise provided, the difference shall be referred to and settled by a single arbitrator to be agreed between the parties or, failing agreement, to be appointed, on the application of either party (after notice in writing to the other)—
(a)in the case of a difference under section 40 (Approval of plans by local authorities, etc.) relating to works in the Forest Recreation Ground, by the President of the Landscape Institute;
(b)in the case of any other difference arising under the said section 40, by the President of the Royal Town Planning Institute following consultation with the President of the Royal Institute of British Architects;
(c)in any other case, by the President of the Institution of Civil Engineers.