“Compensation in respect of any compulsory acquisition shall be assessed in accordance with the following rules: …. (2) The value of land shall, subject as hereinafter provided, be taken to be the amount which the land if sold in the open market by a willing seller might be expected to realise. …. (6) The provisions of rule (2) shall not affect the assessment of compensation for disturbance or any other matter not directly based on the value of land.”