A highway authority shall not, in the exercise of functions relating to cattle-grids conferred by this Part of this Act, carry out any work in—
except with the consent of the person liable to maintain the bridge or of the railway undertakers, as the case may be.
Where consent under this section is withheld the highway authority may refer the matter to the Minister and if, after affording to the highway authority and to the said person, or to the railway undertakers, as the case may be, an opportunity of being heard by a person appointed by the Minister for the purpose, and considering his report, the Minister so directs, the work may be carried out notwithstanding that the consent has been withheld but subject to compliance with any conditions which the Minister may impose.