in the event of a breach by the farmer of the requirements referred to in article 4, the Minister may give the farmer notice in writing terminating the agreement forthwith and may recover from the farmer as a debt an amount equivalent to the payments made by the Minister under the agreement or such part thereof as the Minister may specify;

any question arising under the agreement as to whether there has been a breach of any of the requirements referred to in article 4 shall be referred to and determined by a single arbitrator to be agreed between the parties or in default of agreement to be appointed by the President of the Royal Institution of Chartered Surveyors and in accordance with the provisions of the Arbitration Act 19504 or any statutory modification or re-enactment thereof for the time being in force.