All contracts entered into by or on behalf of the Commissioners of Customs in respect of any lands or hereditaments in Great Britain, the Isle of Man, or the Channel Islands for the service of Her Majesty's Customs, and not at the passing of this Act fully performed and completed, may be enforced and shall be performed and completed for the public service in like manner as if the Commissioners of Works had been parties thereto instead of the Commissioners of Customs.