It is inappropriate, if not meaningless, to attempt to apply limit state design methods, such as those encapsulated in Eurocode 7, to the design of primary support for tunnels in rock, particularly weak rock or any rock under high stress. By reference to some 41 case histories of major tunnel failures, it is shown that more than 85% were the result of unexpected geology or hydrogeology. It is submitted that the unknowns and uncertainties in geology and hydrology cannot be properly dealt with by applying codified factors to geotechnical parameters. It is concluded that working stress methods should be retained for tunnel support design, and that such design would benefit, far more, from competent geological and hydrogeological understanding, than from faith in Code factors.