The circumstance that advice of different categories was contained in some of the disputed documents did not, of itself, give rise to any insurmountable problem. If privileged material was contained in one distinct part of a document and non-privileged material was contained in another, protection of the confidentiality of the privileged part of the document would not, as the Act itself recognizes (see, e.g., ss. 22, 33(3), 33A(3), 34(3), 35(3), 36(4), 58(2), 64(2) and (4)), ordinarily require that that part which was not covered by privilege should also be immune from production: see, e.g., Ainsworth v. Wilding [12] ; Great Atlantic Insurance Co. v. Home Insurance Co. [13] ; Brambles Holdings Ltd. v. Trade Practices Commission [No. 3] [14] . If it were not possible to classify the contents of the document into distinct parts, it would be necessary to determine whether the contents as a whole were outside the protection of legal professional privilege for the reason that, notwithstanding the professional legal advice, they did not satisfy what has conveniently, if somewhat loosely, been referred to as "the sole purpose" test: see Grant v. Downs [15] . That test looks to the purpose for which the contents of a document were brought into existence. To adapt the words of Stephen, Mason and Murphy JJ. in Grant v. Downs, a document (or a severable part of a document) will not be protected by legal professional privilege if it "would have been brought into existence in any event" for purposes other than that which attracts legal professional privilege: and cf., e.g., the Birmingham & Midland Motor Omnibus Co. Case [16] ; Longthorn [17] ; Comment, "Agents' Reports and the Attorney-Client Privilege", University of Chicago Law Review, vol. 21 (1954), 752, at pp. 754-755. Applying that test to the circumstances of the present case, a document containing general policy advice from the "freedom of information" section of the Attorney-General's Department would not prima facie enjoy the protection of legal professional privilege if the moving purpose underlying its preparation had been to convey advice about the observance and application of general government policy proffered by the section of the Department responsible for the general administration of the Act. For the document to be protected, the cause of its existence, in the sense of both causans and sine qua non, must be the seeking or provision of professional legal advice. That is not, of course, to say that every statement in a letter from a professional legal adviser must be scrutinized to see whether it contains other than legal advice. Ordinarily, a letter from a professional legal adviser will be written only in his character as such and only for the purpose of furnishing professional legal advice. The cases where such scrutiny will ordinarily be necessary are cases like the present where a letter is or may be written in one or both of two capacities: e.g., a letter written to the secretary of a company by a person who is both a director of the company and the company's solicitor.