If any land, whether open or enclosed, not vesting in ¹[²[the Corporation]] and not occupied by any building is within the regular line of a public street or if a platform, verandah, step, compound wall, hedge or fence or some other structure external to a building abutting on a public street or a portion of such platform, verandah, step, compound wall, hedge, fence or other structure is within the regular line of such street the Commissioner may, after giving to the owner of the land or building not less than seven clear days' notice of his intention so to do, take possession on behalf of ¹[²[the Corporation]] of the said land with its enclosing wall, hedge or fence, if any, or of the said platform, verandah, step, compound wall, hedge, fence or other structure or of any portion thereof which is within the regular line of the public street and, if necessary, clear the same and the land so acquired shall thereupon be deemed to be a part of the public street and shall vest in ¹[²[the Corporation]]:
     Provided that where the land or building is vested in the Union or a State the Commissioner shall not take posession thereof without the previous sanction of the Central ³[Government].