s 143D Proceedings for possession
(1) The landlord may only bring a demoted tenancy to an end by obtaining — (a) an order of the court for the possession of the dwelling-house, and (b) the execution of the order. (1A) In such a case, the tenancy ends when the order is executed. (2) The court must make an order for possession unless it thinks that the procedure under sections 143E and 143F has not been followed. (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .