199 Knightsbridge Development Ltd v WSP UK Ltd [2014] EWHC 43 (TCC), [2014] All ER (D) 06 (Mar)
A professional person did not warrant that the course of action that he took or advised his client to follow would be successful. If a professional person adopted or advised a course of action which, although unsuccessful or shown to be wrong, was a course of action that was in accord with or was adopted at the time by a responsible body of opinion held by practitioners in that discipline, he would not be negligent provided that that body of opinion had a logical or rational basis. If the exponents of the responsible body of opinion relied on could not demonstrate that the opinion had a logical or rational basis, the defence would be unlikely to succeed. If the reason why the impugned course of action or advice was wrong was that the professional man in question and others in his position did not identify or foresee a particular risk or sequence of events, then there was probably no room for the application of the principle in Bolam. In
