Nothing in this Act contained shall authorize any Person to purchase, take, use, or interfere with, or the Commissioners to make any Order with respect to any Land, Soil, or Water, or any Right in respect thereof, the Management or Control of which may be vested in the Commissioners of Her Majesty's Works and Public Buildings on behalf of or in trust for Her Majesty or the Public, without the Consent in Writing of the last-mentioned Commissioners, which they are hereby authorized to give.