From Law wiki, the wiki for law research

The plaintiff asked his insurance company about the financial soundness of an associated company. On the basis of the information he received not only did he keep his investment in the company be he invested more money. This information proved to be incorrect, and the plaintiff suffered financial loss. The Privy Council adopted a narrow approach to the requirement for special skill or knowledge on the part of the defendant. The majority felt liability should arise only where a defendant professes such expertise in the field in which advice is given, not in other (even if slightly overlapping) areas. Hence, the plaintiff lost his case.

However, in their dissent, Lords Reid and Morris suggested liability might arise in such cases if the plaintiff in such cases made it clear he wanted considered advice and intended to act upon it. This was particularly so where the considered advice was sought from a businessman in the course of his business. In subsequent decisions this minority view, that the 'special relationship' could include any business or professional relationship, has gained acceptance. For instance, in Esso Petroleum Co Ltd v Mardon (1976), the Court of Appeal held that although the defendants were not in the business of giving advice, they had 'special knowledge and skill' in estimating the petrol output at a filling station they franchised and which the plaintiff relied upon when purchasing the station.

The significance of Mutual Life is the court's narrow reading of the Hedley Byrne principle (i.e. that a duty of care can exist in the context of a 'special relationship' between two parties where one has suffered pure economic loss in connection with the others' negligent misstatement), one that was eventually widened in subsequent cases. Here, the court held that liability under the Hedley principle should be restricted to defendants where the primary purpose of business was providing the information or advice in question or where a representation to this effect had been made. However, in Esso Petroleum Co Ltd v Mardon (1976), the court ruled that liability under the Hedley Byrne principle could be extended even to defendants who merely held themselves out as possessing the requisite knowledge and skill relied upon by the defendant.

See also Hedley Byrne v Heller (1963), Esso Petroleum Co Ltd v Mardon (1976).