No Building shall, without the Consent in Writing of the Metropolitan Board of Works, be erected beyond the regular Line of Buildings in the Street in which the same is situate, in case the Distance of such Line of Buildings from the Highway do not exceed Thirty Feet, or within Thirty Feet of the Highway where the Distance of the Line of Buildings therefrom amounts to or exceeds Thirty Feet, notwithstanding there being Gardens or vacant Spaces between the Line of Buildings and the Highway ; and in case any Building be erected contrary to this Enactment, it shall be lawful for the Vestry or District Board in whose Parish or District such Building is situate to cause the same to be demolished or set back (as the Case may require), and to recover the Expenses incurred by them from the Owner of the Premises in manner provided by this Act.