It shall be lawful for the President or the Vice-President of a Board, or the Chief Executive Officer, or the Health Officer or any person specially authorised by the Chief Executive Officer, or the Health Officer or for any other person authorised by general or special order of a Board in this behalf, to enter into or upon any building or land with or without assistants or workmen in order to make any inquiry, inspection, measurement, valuation or survey, or to execute any work, which is authorised by or under this Act or which it is necessary to make or execute for any of the purposes or in pursuance of any of the provisions of this Act or of any rule, bye-law or order made thereunder:
     Provided that nothing in this section shall be deemed to confer upon any person any power such as is referred to in section 274 or section 283 or to authorise the conferment upon any person of any such power.