21(1)The Board and their surveyors and officers may at all reasonable times in the day, upon giving on the first occasion not less than 7 days', and on subsequent occasions not less than 3 days', previous notice in writing to the occupier and to the owner if he is not the occupier, enter upon, examine and lay open any land which may be purchased compulsorily under this Order for the purpose of surveying, measuring, taking levels, examining works and valuing that land or for any other purpose ancillary to the powers conferred by this Order.
(2)Any person entering land under subsection (1) above on behalf of the Board shall, if so required, produce written evidence of his identity and of his authority to do so.
(3)In the exercise of the powers of subsection (1) above the Board and their surveyors and officers shall cause as little detriment or inconvenience to any person as circumstances allow, and the Board shall, subject to the provisions of this Order, make compensation to the owners and occupiers of any land injuriously affected by the exercise of those powers, to be determined in case of dispute by the tribunal.