15. The Company shall repay to the authority the agreed proportion of, or (as the case may be) all reasonable costs, charges and expenses properly incurred by the authority—
(a)in, or in connection with, the undertaking of any works or the carrying out of any operations on behalf of the Company under paragraph 9 above;
(b)in respect of the employment of any inspectors and other persons whom it shall be reasonably necessary to appoint for inspecting and guarding airport property and for preventing, as far as may be reasonably practicable, interference, obstructions, danger or accident arising from the construction or failure of the authorised works;
(c)in respect of any additional temporary lighting of airport property in the vicinity of the authorised works, being lighting made reasonably necessary during and by reason of the construction or failure of the authorised works; and
(d)in respect of the preparation and approval of all plans provided for in this Schedule and of the scheme referred to in paragraph 6(1)(a) above.