Not at any time without the license in writing of the Landlord first obtained nor except in accordance with the plans and specifications previously submitted in triplicate to the Landlord and approved in writing by the Landlord and to its satisfaction to make any alteration or addition whatsoever in or to the Premises either externally or internally or to make any alterations or aperture in the plan walls timbers elevations or architectural appearance thereof nor to cut or remove the main walls timbers floors or ceilings of the Flat unless for the purpose of repairing and making good any defect therein nor to do or suffer in or upon the Flat any wilful or voluntary waste or spoil