It is convenient first to discuss the circumstances in which an agent may himself or itself be liable where his or its principal is not disclosed.
There is some confusion in this area of the law. It arises from the failure to bear in mind the clear distinction between the non-disclosure of the name of a principal and non-disclosure of the fact that there is one, that is, non-disclosure of the fact of agency.
The distinction is discussed by Professor Reynolds, Reader in Law, University of Oxford, in "Practical Problems of the Undisclosed Principal Doctrine" (1983) Current Legal Problems. The mere fact that an agent does not identify the principal for whom he acts does not make the agent personally liable, unless on the proper interpretation of the contract he has contracted as a party to the contract, not as agent. In other words, an agent is not personally liable, even when acting for an undisclosed principal, unless on the proper interpretation of the contract he is a party to it as though he were principal. The question is one of interpretation of the contract: Scott v Geoghegan and Sons Pty Ltd (1969) 43 ALJR 243, per Taylor J, at 245.
The law was conveniently summarised by Professor Reynolds, at 120:
... the situation may be analysed as one where the principal is not undisclosed but rather unnamed or unidentified, ie his existence and connection with the transaction must be deemed to have been in some measure contemplated from the outset by the third party, though his name was not known. For such a situation recent case-law indicates that the prima facie rule is that the contract is between the third party and the principal. (N. and J. Vlassopulos Ltd v Ney Shipping Ltd (The Santa Carina) [1977] 1 Lloyd's Rep. 478.) The agent may sometimes additionally be liable, and even entitled: but his is not the primary liability, and such a result would seem to require some special feature, such as the use of a written contract upon the wording of which the agent appears to undertake liability, (e.g. Tudor Marine Ltd v Tradax Export SA (The Virgo) [1976] 2 Lloyd's Rep. 135) or the proof of a trade custom that the agent undertakes additional liability, (e.g. Fleet v Murton (1871) LR 7 QB 126) or other indications displacing the normal rule, (e.g. Franklyn v Lamond (1847) 4 CB 637 (auctioneer)).
This last set of rules relating to the unnamed principal, it should be noted, is considerably different from those governing the true undisclosed principal situation; and this makes it important to know whether on any set of facts the principal, if there is one, should be treated as truly undisclosed or merely as unnamed, though many old authorities do not make the distinction, (e.g. Scrutton, Charterparties (1st ed. 1886), Art. 14 (referring to a signature 'as agents for merchants' as an example of an undisclosed principal case.)).[5]