Harbutt's "Plasticine" Ltd v Wayne Tank and Pump Co Ltd [1970] is an English contract law case involving the quantum of damages and the concept of fundamental breach. It was heard in the Court of Appeal by Lord Denning MR, Widgery LJ and Cross LJ. The concept of fundamental breach has not proved to be durable, and that aspect of this case was disapproved in the House of Lords' decision in Photoproductions v Securicor.